luisantunesdeveloper/request-multi-streams

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Function getStreams has 46 lines of code (exceeds 25 allowed). Consider refactoring.
Open

function getStreams() {
  const emitters = httpMultiStreams.streams(reqs);

  if (emitters) {
    for (var name in emitters) {
Severity: Minor
Found in examples/request-multi-streams.js - About 1 hr to fix

    Function get has 34 lines of code (exceeds 25 allowed). Consider refactoring.
    Open

    function get(args) {
      const iterable = createIterable(
        args.numberOfRequests || defaultNumberOfRequests
      );
      const emitter = new eventEmitter();
    Severity: Minor
    Found in request-multi-streams.js - About 1 hr to fix

      Similar blocks of code found in 2 locations. Consider refactoring.
      Open

              console.log(
                chalk.yellow(
                  `Request ${data.reqNumber} for ${
                    data.args.options.url
                  }: got a response`
      Severity: Minor
      Found in examples/request-multi-streams.js and 1 other location - About 40 mins to fix
      examples/request-multi-streams.js on lines 71..77

      Duplicated Code

      Duplicated code can lead to software that is hard to understand and difficult to change. The Don't Repeat Yourself (DRY) principle states:

      Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.

      When you violate DRY, bugs and maintenance problems are sure to follow. Duplicated code has a tendency to both continue to replicate and also to diverge (leaving bugs as two similar implementations differ in subtle ways).

      Tuning

      This issue has a mass of 48.

      We set useful threshold defaults for the languages we support but you may want to adjust these settings based on your project guidelines.

      The threshold configuration represents the minimum mass a code block must have to be analyzed for duplication. The lower the threshold, the more fine-grained the comparison.

      If the engine is too easily reporting duplication, try raising the threshold. If you suspect that the engine isn't catching enough duplication, try lowering the threshold. The best setting tends to differ from language to language.

      See codeclimate-duplication's documentation for more information about tuning the mass threshold in your .codeclimate.yml.

      Refactorings

      Further Reading

      Similar blocks of code found in 2 locations. Consider refactoring.
      Open

              console.log(
                chalk.green(
                  `Request ${end.reqNumber} for ${
                    end.args.options.url
                  }: finished with sucess`
      Severity: Minor
      Found in examples/request-multi-streams.js and 1 other location - About 40 mins to fix
      examples/request-multi-streams.js on lines 46..52

      Duplicated Code

      Duplicated code can lead to software that is hard to understand and difficult to change. The Don't Repeat Yourself (DRY) principle states:

      Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.

      When you violate DRY, bugs and maintenance problems are sure to follow. Duplicated code has a tendency to both continue to replicate and also to diverge (leaving bugs as two similar implementations differ in subtle ways).

      Tuning

      This issue has a mass of 48.

      We set useful threshold defaults for the languages we support but you may want to adjust these settings based on your project guidelines.

      The threshold configuration represents the minimum mass a code block must have to be analyzed for duplication. The lower the threshold, the more fine-grained the comparison.

      If the engine is too easily reporting duplication, try raising the threshold. If you suspect that the engine isn't catching enough duplication, try lowering the threshold. The best setting tends to differ from language to language.

      See codeclimate-duplication's documentation for more information about tuning the mass threshold in your .codeclimate.yml.

      Refactorings

      Further Reading

      Unexpected trailing comma.
      Open

        numberOfRequests: 10, // Not the same as retries
      Severity: Minor
      Found in examples/request-multi-streams.js by eslint

      require or disallow trailing commas (comma-dangle)

      Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.

      var foo = {
          bar: "baz",
          qux: "quux",
      };

      Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:

      Less clear:

      var foo = {
      -    bar: "baz",
      -    qux: "quux"
      +    bar: "baz"
       };

      More clear:

      var foo = {
           bar: "baz",
      -    qux: "quux",
       };

      Rule Details

      This rule enforces consistent use of trailing commas in object and array literals.

      Options

      This rule has a string option or an object option:

      {
          "comma-dangle": ["error", "never"],
          // or
          "comma-dangle": ["error", {
              "arrays": "never",
              "objects": "never",
              "imports": "never",
              "exports": "never",
              "functions": "ignore",
          }]
      }
      • "never" (default) disallows trailing commas
      • "always" requires trailing commas
      • "always-multiline" requires trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }
      • "only-multiline" allows (but does not require) trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }

      Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.

      You can also use an object option to configure this rule for each type of syntax. Each of the following options can be set to "never", "always", "always-multiline", "only-multiline", or "ignore". The default for each option is "never" unless otherwise specified.

      • arrays is for array literals and array patterns of destructuring. (e.g. let [a,] = [1,];)
      • objects is for object literals and object patterns of destructuring. (e.g. let {a,} = {a: 1};)
      • imports is for import declarations of ES Modules. (e.g. import {a,} from "foo";)
      • exports is for export declarations of ES Modules. (e.g. export {a,};)
      • functions is for function declarations and function calls. (e.g. (function(a,){ })(b,);)
        functions is set to "ignore" by default for consistency with the string option.

      never

      Examples of incorrect code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      Examples of correct code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      always

      Examples of incorrect code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      always-multiline

      Examples of incorrect code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      only-multiline

      Examples of incorrect code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];

      Examples of correct code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      functions

      Examples of incorrect code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      Examples of correct code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of incorrect code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of correct code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      When Not To Use It

      You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/

      Unexpected trailing comma.
      Open

                error: error,
      Severity: Minor
      Found in request-multi-streams.js by eslint

      require or disallow trailing commas (comma-dangle)

      Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.

      var foo = {
          bar: "baz",
          qux: "quux",
      };

      Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:

      Less clear:

      var foo = {
      -    bar: "baz",
      -    qux: "quux"
      +    bar: "baz"
       };

      More clear:

      var foo = {
           bar: "baz",
      -    qux: "quux",
       };

      Rule Details

      This rule enforces consistent use of trailing commas in object and array literals.

      Options

      This rule has a string option or an object option:

      {
          "comma-dangle": ["error", "never"],
          // or
          "comma-dangle": ["error", {
              "arrays": "never",
              "objects": "never",
              "imports": "never",
              "exports": "never",
              "functions": "ignore",
          }]
      }
      • "never" (default) disallows trailing commas
      • "always" requires trailing commas
      • "always-multiline" requires trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }
      • "only-multiline" allows (but does not require) trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }

      Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.

      You can also use an object option to configure this rule for each type of syntax. Each of the following options can be set to "never", "always", "always-multiline", "only-multiline", or "ignore". The default for each option is "never" unless otherwise specified.

      • arrays is for array literals and array patterns of destructuring. (e.g. let [a,] = [1,];)
      • objects is for object literals and object patterns of destructuring. (e.g. let {a,} = {a: 1};)
      • imports is for import declarations of ES Modules. (e.g. import {a,} from "foo";)
      • exports is for export declarations of ES Modules. (e.g. export {a,};)
      • functions is for function declarations and function calls. (e.g. (function(a,){ })(b,);)
        functions is set to "ignore" by default for consistency with the string option.

      never

      Examples of incorrect code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      Examples of correct code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      always

      Examples of incorrect code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      always-multiline

      Examples of incorrect code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      only-multiline

      Examples of incorrect code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];

      Examples of correct code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      functions

      Examples of incorrect code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      Examples of correct code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of incorrect code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of correct code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      When Not To Use It

      You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/

      The body of a for-in should be wrapped in an if statement to filter unwanted properties from the prototype.
      Open

          for (var name in emitters) {
      Severity: Minor
      Found in examples/request-multi-streams.js by eslint

      Require Guarding for-in (guard-for-in)

      Looping over objects with a for in loop will include properties that are inherited through the prototype chain. This behavior can lead to unexpected items in your for loop.

      for (key in foo) {
          doSomething(key);
      }

      Note that simply checking foo.hasOwnProperty(key) is likely to cause an error in some cases; see [no-prototype-builtins](no-prototype-builtins.md).

      Rule Details

      This rule is aimed at preventing unexpected behavior that could arise from using a for in loop without filtering the results in the loop. As such, it will warn when for in loops do not filter their results with an if statement.

      Examples of incorrect code for this rule:

      /*eslint guard-for-in: "error"*/
      
      for (key in foo) {
          doSomething(key);
      }

      Examples of correct code for this rule:

      /*eslint guard-for-in: "error"*/
      
      for (key in foo) {
          if (Object.prototype.hasOwnProperty.call(foo, key)) {
              doSomething(key);
          }
          if ({}.hasOwnProperty.call(foo, key)) {
              doSomething(key);
          }
      }

      Related Rules

      • [no-prototype-builtins](no-prototype-builtins.md)

      Further Reading

      Unexpected trailing comma.
      Open

          delay: 10, // Only start to emit after 1000ms delay, defaults to 0ms
      Severity: Minor
      Found in examples/request-multi-streams.js by eslint

      require or disallow trailing commas (comma-dangle)

      Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.

      var foo = {
          bar: "baz",
          qux: "quux",
      };

      Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:

      Less clear:

      var foo = {
      -    bar: "baz",
      -    qux: "quux"
      +    bar: "baz"
       };

      More clear:

      var foo = {
           bar: "baz",
      -    qux: "quux",
       };

      Rule Details

      This rule enforces consistent use of trailing commas in object and array literals.

      Options

      This rule has a string option or an object option:

      {
          "comma-dangle": ["error", "never"],
          // or
          "comma-dangle": ["error", {
              "arrays": "never",
              "objects": "never",
              "imports": "never",
              "exports": "never",
              "functions": "ignore",
          }]
      }
      • "never" (default) disallows trailing commas
      • "always" requires trailing commas
      • "always-multiline" requires trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }
      • "only-multiline" allows (but does not require) trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }

      Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.

      You can also use an object option to configure this rule for each type of syntax. Each of the following options can be set to "never", "always", "always-multiline", "only-multiline", or "ignore". The default for each option is "never" unless otherwise specified.

      • arrays is for array literals and array patterns of destructuring. (e.g. let [a,] = [1,];)
      • objects is for object literals and object patterns of destructuring. (e.g. let {a,} = {a: 1};)
      • imports is for import declarations of ES Modules. (e.g. import {a,} from "foo";)
      • exports is for export declarations of ES Modules. (e.g. export {a,};)
      • functions is for function declarations and function calls. (e.g. (function(a,){ })(b,);)
        functions is set to "ignore" by default for consistency with the string option.

      never

      Examples of incorrect code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      Examples of correct code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      always

      Examples of incorrect code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      always-multiline

      Examples of incorrect code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      only-multiline

      Examples of incorrect code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];

      Examples of correct code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      functions

      Examples of incorrect code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      Examples of correct code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of incorrect code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of correct code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      When Not To Use It

      You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/

      Unexpected trailing comma.
      Open

          url: 'http://www.textfiles.com/fun/acronym.txt',
      Severity: Minor
      Found in examples/request-multi-streams.js by eslint

      require or disallow trailing commas (comma-dangle)

      Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.

      var foo = {
          bar: "baz",
          qux: "quux",
      };

      Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:

      Less clear:

      var foo = {
      -    bar: "baz",
      -    qux: "quux"
      +    bar: "baz"
       };

      More clear:

      var foo = {
           bar: "baz",
      -    qux: "quux",
       };

      Rule Details

      This rule enforces consistent use of trailing commas in object and array literals.

      Options

      This rule has a string option or an object option:

      {
          "comma-dangle": ["error", "never"],
          // or
          "comma-dangle": ["error", {
              "arrays": "never",
              "objects": "never",
              "imports": "never",
              "exports": "never",
              "functions": "ignore",
          }]
      }
      • "never" (default) disallows trailing commas
      • "always" requires trailing commas
      • "always-multiline" requires trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }
      • "only-multiline" allows (but does not require) trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }

      Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.

      You can also use an object option to configure this rule for each type of syntax. Each of the following options can be set to "never", "always", "always-multiline", "only-multiline", or "ignore". The default for each option is "never" unless otherwise specified.

      • arrays is for array literals and array patterns of destructuring. (e.g. let [a,] = [1,];)
      • objects is for object literals and object patterns of destructuring. (e.g. let {a,} = {a: 1};)
      • imports is for import declarations of ES Modules. (e.g. import {a,} from "foo";)
      • exports is for export declarations of ES Modules. (e.g. export {a,};)
      • functions is for function declarations and function calls. (e.g. (function(a,){ })(b,);)
        functions is set to "ignore" by default for consistency with the string option.

      never

      Examples of incorrect code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      Examples of correct code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      always

      Examples of incorrect code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      always-multiline

      Examples of incorrect code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      only-multiline

      Examples of incorrect code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];

      Examples of correct code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      functions

      Examples of incorrect code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      Examples of correct code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of incorrect code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of correct code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      When Not To Use It

      You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/

      Unexpected trailing comma.
      Open

                stream: stream,
      Severity: Minor
      Found in request-multi-streams.js by eslint

      require or disallow trailing commas (comma-dangle)

      Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.

      var foo = {
          bar: "baz",
          qux: "quux",
      };

      Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:

      Less clear:

      var foo = {
      -    bar: "baz",
      -    qux: "quux"
      +    bar: "baz"
       };

      More clear:

      var foo = {
           bar: "baz",
      -    qux: "quux",
       };

      Rule Details

      This rule enforces consistent use of trailing commas in object and array literals.

      Options

      This rule has a string option or an object option:

      {
          "comma-dangle": ["error", "never"],
          // or
          "comma-dangle": ["error", {
              "arrays": "never",
              "objects": "never",
              "imports": "never",
              "exports": "never",
              "functions": "ignore",
          }]
      }
      • "never" (default) disallows trailing commas
      • "always" requires trailing commas
      • "always-multiline" requires trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }
      • "only-multiline" allows (but does not require) trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }

      Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.

      You can also use an object option to configure this rule for each type of syntax. Each of the following options can be set to "never", "always", "always-multiline", "only-multiline", or "ignore". The default for each option is "never" unless otherwise specified.

      • arrays is for array literals and array patterns of destructuring. (e.g. let [a,] = [1,];)
      • objects is for object literals and object patterns of destructuring. (e.g. let {a,} = {a: 1};)
      • imports is for import declarations of ES Modules. (e.g. import {a,} from "foo";)
      • exports is for export declarations of ES Modules. (e.g. export {a,};)
      • functions is for function declarations and function calls. (e.g. (function(a,){ })(b,);)
        functions is set to "ignore" by default for consistency with the string option.

      never

      Examples of incorrect code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      Examples of correct code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      always

      Examples of incorrect code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      always-multiline

      Examples of incorrect code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      only-multiline

      Examples of incorrect code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];

      Examples of correct code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      functions

      Examples of incorrect code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      Examples of correct code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of incorrect code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of correct code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      When Not To Use It

      You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/

      Unexpected trailing comma.
      Open

        streams: streams,
      Severity: Minor
      Found in request-multi-streams.js by eslint

      require or disallow trailing commas (comma-dangle)

      Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.

      var foo = {
          bar: "baz",
          qux: "quux",
      };

      Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:

      Less clear:

      var foo = {
      -    bar: "baz",
      -    qux: "quux"
      +    bar: "baz"
       };

      More clear:

      var foo = {
           bar: "baz",
      -    qux: "quux",
       };

      Rule Details

      This rule enforces consistent use of trailing commas in object and array literals.

      Options

      This rule has a string option or an object option:

      {
          "comma-dangle": ["error", "never"],
          // or
          "comma-dangle": ["error", {
              "arrays": "never",
              "objects": "never",
              "imports": "never",
              "exports": "never",
              "functions": "ignore",
          }]
      }
      • "never" (default) disallows trailing commas
      • "always" requires trailing commas
      • "always-multiline" requires trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }
      • "only-multiline" allows (but does not require) trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }

      Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.

      You can also use an object option to configure this rule for each type of syntax. Each of the following options can be set to "never", "always", "always-multiline", "only-multiline", or "ignore". The default for each option is "never" unless otherwise specified.

      • arrays is for array literals and array patterns of destructuring. (e.g. let [a,] = [1,];)
      • objects is for object literals and object patterns of destructuring. (e.g. let {a,} = {a: 1};)
      • imports is for import declarations of ES Modules. (e.g. import {a,} from "foo";)
      • exports is for export declarations of ES Modules. (e.g. export {a,};)
      • functions is for function declarations and function calls. (e.g. (function(a,){ })(b,);)
        functions is set to "ignore" by default for consistency with the string option.

      never

      Examples of incorrect code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      Examples of correct code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      always

      Examples of incorrect code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      always-multiline

      Examples of incorrect code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      only-multiline

      Examples of incorrect code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];

      Examples of correct code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      functions

      Examples of incorrect code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      Examples of correct code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of incorrect code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of correct code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      When Not To Use It

      You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/

      Unexpected trailing comma.
      Open

        numberOfRequests: 10, // Not the same as retries
      Severity: Minor
      Found in examples/request-multi-streams.js by eslint

      require or disallow trailing commas (comma-dangle)

      Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.

      var foo = {
          bar: "baz",
          qux: "quux",
      };

      Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:

      Less clear:

      var foo = {
      -    bar: "baz",
      -    qux: "quux"
      +    bar: "baz"
       };

      More clear:

      var foo = {
           bar: "baz",
      -    qux: "quux",
       };

      Rule Details

      This rule enforces consistent use of trailing commas in object and array literals.

      Options

      This rule has a string option or an object option:

      {
          "comma-dangle": ["error", "never"],
          // or
          "comma-dangle": ["error", {
              "arrays": "never",
              "objects": "never",
              "imports": "never",
              "exports": "never",
              "functions": "ignore",
          }]
      }
      • "never" (default) disallows trailing commas
      • "always" requires trailing commas
      • "always-multiline" requires trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }
      • "only-multiline" allows (but does not require) trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }

      Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.

      You can also use an object option to configure this rule for each type of syntax. Each of the following options can be set to "never", "always", "always-multiline", "only-multiline", or "ignore". The default for each option is "never" unless otherwise specified.

      • arrays is for array literals and array patterns of destructuring. (e.g. let [a,] = [1,];)
      • objects is for object literals and object patterns of destructuring. (e.g. let {a,} = {a: 1};)
      • imports is for import declarations of ES Modules. (e.g. import {a,} from "foo";)
      • exports is for export declarations of ES Modules. (e.g. export {a,};)
      • functions is for function declarations and function calls. (e.g. (function(a,){ })(b,);)
        functions is set to "ignore" by default for consistency with the string option.

      never

      Examples of incorrect code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      Examples of correct code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      always

      Examples of incorrect code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      always-multiline

      Examples of incorrect code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      only-multiline

      Examples of incorrect code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];

      Examples of correct code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      functions

      Examples of incorrect code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      Examples of correct code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of incorrect code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of correct code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      When Not To Use It

      You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/

      Unexpected trailing comma.
      Open

            'https://cdn.pixabay.com/photo/2014/03/27/21/10/waterfall-299685_1280.jpg',
      Severity: Minor
      Found in examples/request-multi-streams.js by eslint

      require or disallow trailing commas (comma-dangle)

      Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.

      var foo = {
          bar: "baz",
          qux: "quux",
      };

      Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:

      Less clear:

      var foo = {
      -    bar: "baz",
      -    qux: "quux"
      +    bar: "baz"
       };

      More clear:

      var foo = {
           bar: "baz",
      -    qux: "quux",
       };

      Rule Details

      This rule enforces consistent use of trailing commas in object and array literals.

      Options

      This rule has a string option or an object option:

      {
          "comma-dangle": ["error", "never"],
          // or
          "comma-dangle": ["error", {
              "arrays": "never",
              "objects": "never",
              "imports": "never",
              "exports": "never",
              "functions": "ignore",
          }]
      }
      • "never" (default) disallows trailing commas
      • "always" requires trailing commas
      • "always-multiline" requires trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }
      • "only-multiline" allows (but does not require) trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }

      Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.

      You can also use an object option to configure this rule for each type of syntax. Each of the following options can be set to "never", "always", "always-multiline", "only-multiline", or "ignore". The default for each option is "never" unless otherwise specified.

      • arrays is for array literals and array patterns of destructuring. (e.g. let [a,] = [1,];)
      • objects is for object literals and object patterns of destructuring. (e.g. let {a,} = {a: 1};)
      • imports is for import declarations of ES Modules. (e.g. import {a,} from "foo";)
      • exports is for export declarations of ES Modules. (e.g. export {a,};)
      • functions is for function declarations and function calls. (e.g. (function(a,){ })(b,);)
        functions is set to "ignore" by default for consistency with the string option.

      never

      Examples of incorrect code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      Examples of correct code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      always

      Examples of incorrect code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      always-multiline

      Examples of incorrect code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      only-multiline

      Examples of incorrect code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];

      Examples of correct code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      functions

      Examples of incorrect code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      Examples of correct code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of incorrect code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of correct code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      When Not To Use It

      You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/

      Don't make functions within a loop.
      Open

            emitters[name].on('response', data => {
      Severity: Minor
      Found in examples/request-multi-streams.js by eslint

      Disallow Functions in Loops (no-loop-func)

      Writing functions within loops tends to result in errors due to the way the function creates a closure around the loop. For example:

      for (var i = 0; i < 10; i++) {
          funcs[i] = function() {
              return i;
          };
      }

      In this case, you would expect each function created within the loop to return a different number. In reality, each function returns 10, because that was the last value of i in the scope.

      let or const mitigate this problem.

      /*eslint-env es6*/
      
      for (let i = 0; i < 10; i++) {
          funcs[i] = function() {
              return i;
          };
      }

      In this case, each function created within the loop returns a different number as expected.

      Rule Details

      This error is raised to highlight a piece of code that may not work as you expect it to and could also indicate a misunderstanding of how the language works. Your code may run without any problems if you do not fix this error, but in some situations it could behave unexpectedly.

      Examples of incorrect code for this rule:

      /*eslint no-loop-func: "error"*/
      /*eslint-env es6*/
      
      for (var i=10; i; i--) {
          (function() { return i; })();
      }
      
      while(i) {
          var a = function() { return i; };
          a();
      }
      
      do {
          function a() { return i; };
          a();
      } while (i);
      
      let foo = 0;
      for (let i=10; i; i--) {
          // Bad, function is referencing block scoped variable in the outer scope.
          var a = function() { return foo; };
          a();
      }

      Examples of correct code for this rule:

      /*eslint no-loop-func: "error"*/
      /*eslint-env es6*/
      
      var a = function() {};
      
      for (var i=10; i; i--) {
          a();
      }
      
      for (var i=10; i; i--) {
          var a = function() {}; // OK, no references to variables in the outer scopes.
          a();
      }
      
      for (let i=10; i; i--) {
          var a = function() { return i; }; // OK, all references are referring to block scoped variables in the loop.
          a();
      }
      
      var foo = 100;
      for (let i=10; i; i--) {
          var a = function() { return foo; }; // OK, all references are referring to never modified variables.
          a();
      }
      //... no modifications of foo after this loop ...

      Source: http://eslint.org/docs/rules/

      Unexpected trailing comma.
      Open

                progress: progress,
      Severity: Minor
      Found in request-multi-streams.js by eslint

      require or disallow trailing commas (comma-dangle)

      Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec. However, IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.

      var foo = {
          bar: "baz",
          qux: "quux",
      };

      Trailing commas simplify adding and removing items to objects and arrays, since only the lines you are modifying must be touched. Another argument in favor of trailing commas is that it improves the clarity of diffs when an item is added or removed from an object or array:

      Less clear:

      var foo = {
      -    bar: "baz",
      -    qux: "quux"
      +    bar: "baz"
       };

      More clear:

      var foo = {
           bar: "baz",
      -    qux: "quux",
       };

      Rule Details

      This rule enforces consistent use of trailing commas in object and array literals.

      Options

      This rule has a string option or an object option:

      {
          "comma-dangle": ["error", "never"],
          // or
          "comma-dangle": ["error", {
              "arrays": "never",
              "objects": "never",
              "imports": "never",
              "exports": "never",
              "functions": "ignore",
          }]
      }
      • "never" (default) disallows trailing commas
      • "always" requires trailing commas
      • "always-multiline" requires trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }
      • "only-multiline" allows (but does not require) trailing commas when the last element or property is in a different line than the closing ] or } and disallows trailing commas when the last element or property is on the same line as the closing ] or }

      Trailing commas in function declarations and function calls are valid syntax since ECMAScript 2017; however, the string option does not check these situations for backwards compatibility.

      You can also use an object option to configure this rule for each type of syntax. Each of the following options can be set to "never", "always", "always-multiline", "only-multiline", or "ignore". The default for each option is "never" unless otherwise specified.

      • arrays is for array literals and array patterns of destructuring. (e.g. let [a,] = [1,];)
      • objects is for object literals and object patterns of destructuring. (e.g. let {a,} = {a: 1};)
      • imports is for import declarations of ES Modules. (e.g. import {a,} from "foo";)
      • exports is for export declarations of ES Modules. (e.g. export {a,};)
      • functions is for function declarations and function calls. (e.g. (function(a,){ })(b,);)
        functions is set to "ignore" by default for consistency with the string option.

      never

      Examples of incorrect code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      Examples of correct code for this rule with the default "never" option:

      /*eslint comma-dangle: ["error", "never"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      always

      Examples of incorrect code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var arr = [1,2];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always" option:

      /*eslint comma-dangle: ["error", "always"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var arr = [1,2,];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      always-multiline

      Examples of incorrect code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      Examples of correct code for this rule with the "always-multiline" option:

      /*eslint comma-dangle: ["error", "always-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });

      only-multiline

      Examples of incorrect code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = { bar: "baz", qux: "quux", };
      
      var arr = [1,2,];
      
      var arr = [1,
          2,];

      Examples of correct code for this rule with the "only-multiline" option:

      /*eslint comma-dangle: ["error", "only-multiline"]*/
      
      var foo = {
          bar: "baz",
          qux: "quux",
      };
      
      var foo = {
          bar: "baz",
          qux: "quux"
      };
      
      var foo = {bar: "baz", qux: "quux"};
      var arr = [1,2];
      
      var arr = [1,
          2];
      
      var arr = [
          1,
          2,
      ];
      
      var arr = [
          1,
          2
      ];
      
      foo({
        bar: "baz",
        qux: "quux",
      });
      
      foo({
        bar: "baz",
        qux: "quux"
      });

      functions

      Examples of incorrect code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      Examples of correct code for this rule with the {"functions": "never"} option:

      /*eslint comma-dangle: ["error", {"functions": "never"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of incorrect code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b) {
      }
      
      foo(a, b);
      new foo(a, b);

      Examples of correct code for this rule with the {"functions": "always"} option:

      /*eslint comma-dangle: ["error", {"functions": "always"}]*/
      
      function foo(a, b,) {
      }
      
      foo(a, b,);
      new foo(a, b,);

      When Not To Use It

      You can turn this rule off if you are not concerned with dangling commas. Source: http://eslint.org/docs/rules/

      Severity
      Category
      Status
      Source
      Language