marcomontalbano/html-miner

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Showing 14 of 14 total issues

File test.js has 498 lines of code (exceeds 250 allowed). Consider refactoring.
Open

const chai = require('chai');

const { assert } = chai;
const fs = require('fs');
const path = require('path');
Severity: Minor
Found in test/test.js - About 7 hrs to fix

    Similar blocks of code found in 3 locations. Consider refactoring.
    Open

                links: {
                    _each_: '.nav-item:not(.dropdown) a',
                    text(arg) { return arg.$scope.text(); },
                    href(arg) { return arg.$scope.attr('href'); },
                },
    Severity: Major
    Found in examples/demo.js and 2 other locations - About 1 hr to fix
    examples/demo.js on lines 33..37
    examples/demo.js on lines 46..50

    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 58.

    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 3 locations. Consider refactoring.
    Open

                button: {
                    _container_: 'a.btn',
                    text(arg) { return arg.$scope.text(); },
                    href(arg) { return arg.$scope.attr('href'); },
                },
    Severity: Major
    Found in examples/demo.js and 2 other locations - About 1 hr to fix
    examples/demo.js on lines 23..27
    examples/demo.js on lines 46..50

    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 58.

    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 3 locations. Consider refactoring.
    Open

                button: {
                    _container_: 'a.btn',
                    text(arg) { return arg.$scope.text(); },
                    href(arg) { return arg.$scope.attr('href'); },
                },
    Severity: Major
    Found in examples/demo.js and 2 other locations - About 1 hr to fix
    examples/demo.js on lines 23..27
    examples/demo.js on lines 33..37

    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 58.

    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

    Function htmlMiner has 27 lines of code (exceeds 25 allowed). Consider refactoring.
    Open

    const htmlMiner = (html, originalSelector, memo) => {
        if (validateHtml(html) === false) {
            return undefined;
        }
    
    
    Severity: Minor
    Found in lib/index.js - About 1 hr to fix

      Function htmlMiner has a Cognitive Complexity of 6 (exceeds 5 allowed). Consider refactoring.
      Open

      const htmlMiner = (html, originalSelector, memo) => {
          if (validateHtml(html) === false) {
              return undefined;
          }
      
      
      Severity: Minor
      Found in lib/index.js - About 25 mins to fix

      Cognitive Complexity

      Cognitive Complexity is a measure of how difficult a unit of code is to intuitively understand. Unlike Cyclomatic Complexity, which determines how difficult your code will be to test, Cognitive Complexity tells you how difficult your code will be to read and comprehend.

      A method's cognitive complexity is based on a few simple rules:

      • Code is not considered more complex when it uses shorthand that the language provides for collapsing multiple statements into one
      • Code is considered more complex for each "break in the linear flow of the code"
      • Code is considered more complex when "flow breaking structures are nested"

      Further reading

      Unexpected parentheses around single function argument having a body with no curly braces
      Open

              elements = _.filter(elements, (o) => o !== undefined);
      Severity: Minor
      Found in lib/index.js by eslint

      Require parens in arrow function arguments (arrow-parens)

      Arrow functions can omit parentheses when they have exactly one parameter. In all other cases the parameter(s) must be wrapped in parentheses. This rule enforces the consistent use of parentheses in arrow functions.

      Rule Details

      This rule enforces parentheses around arrow function parameters regardless of arity. For example:

      /*eslint-env es6*/
      
      // Bad
      a => {}
      
      // Good
      (a) => {}

      Following this style will help you find arrow functions (=>) which may be mistakenly included in a condition when a comparison such as >= was the intent.

      /*eslint-env es6*/
      
      // Bad
      if (a => 2) {
      }
      
      // Good
      if (a >= 2) {
      }

      The rule can also be configured to discourage the use of parens when they are not required:

      /*eslint-env es6*/
      
      // Bad
      (a) => {}
      
      // Good
      a => {}

      Options

      This rule has a string option and an object one.

      String options are:

      • "always" (default) requires parens around arguments in all cases.
      • "as-needed" allows omitting parens when there is only one argument.

      Object properties for variants of the "as-needed" option:

      • "requireForBlockBody": true modifies the as-needed rule in order to require parens if the function body is in an instructions block (surrounded by braces).

      always

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => a);
      a(foo => { if (true) {} });

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      () => {};
      (a) => {};
      (a) => a;
      (a) => {'\n'}
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });

      If Statements

      One of benefits of this option is that it prevents the incorrect use of arrow functions in conditionals:

      /*eslint-env es6*/
      
      var a = 1;
      var b = 2;
      // ...
      if (a => b) {
       console.log('bigger');
      } else {
       console.log('smaller');
      }
      // outputs 'bigger', not smaller as expected

      The contents of the if statement is an arrow function, not a comparison.

      If the arrow function is intentional, it should be wrapped in parens to remove ambiguity.

      /*eslint-env es6*/
      
      var a = 1;
      var b = 0;
      // ...
      if ((a) => b) {
       console.log('truthy value returned');
      } else {
       console.log('falsey value returned');
      }
      // outputs 'truthy value returned'

      The following is another example of this behavior:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = a => b ? c: d;
      // f = ?

      f is an arrow function which takes a as an argument and returns the result of b ? c: d.

      This should be rewritten like so:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = (a) => b ? c: d;

      as-needed

      Examples of incorrect code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => a;
      (a) => {'\n'};
      a.then((foo) => {});
      a.then((foo) => a);
      a((foo) => { if (true) {} });

      Examples of correct code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      () => {};
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      requireForBlockBody

      Examples of incorrect code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => a;
      a => {};
      a => {'\n'};
      a.map((x) => x * x);
      a.map(x => {
        return x * x;
      });
      a.then(foo => {});

      Examples of correct code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => {'\n'};
      a => ({});
      () => {};
      a => a;
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });
      a((foo) => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      Further Reading

      Unexpected parentheses around single function argument having a body with no curly braces
      Open

                      (arg) => arg.scopeData[0],
      Severity: Minor
      Found in test/test.js by eslint

      Require parens in arrow function arguments (arrow-parens)

      Arrow functions can omit parentheses when they have exactly one parameter. In all other cases the parameter(s) must be wrapped in parentheses. This rule enforces the consistent use of parentheses in arrow functions.

      Rule Details

      This rule enforces parentheses around arrow function parameters regardless of arity. For example:

      /*eslint-env es6*/
      
      // Bad
      a => {}
      
      // Good
      (a) => {}

      Following this style will help you find arrow functions (=>) which may be mistakenly included in a condition when a comparison such as >= was the intent.

      /*eslint-env es6*/
      
      // Bad
      if (a => 2) {
      }
      
      // Good
      if (a >= 2) {
      }

      The rule can also be configured to discourage the use of parens when they are not required:

      /*eslint-env es6*/
      
      // Bad
      (a) => {}
      
      // Good
      a => {}

      Options

      This rule has a string option and an object one.

      String options are:

      • "always" (default) requires parens around arguments in all cases.
      • "as-needed" allows omitting parens when there is only one argument.

      Object properties for variants of the "as-needed" option:

      • "requireForBlockBody": true modifies the as-needed rule in order to require parens if the function body is in an instructions block (surrounded by braces).

      always

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => a);
      a(foo => { if (true) {} });

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      () => {};
      (a) => {};
      (a) => a;
      (a) => {'\n'}
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });

      If Statements

      One of benefits of this option is that it prevents the incorrect use of arrow functions in conditionals:

      /*eslint-env es6*/
      
      var a = 1;
      var b = 2;
      // ...
      if (a => b) {
       console.log('bigger');
      } else {
       console.log('smaller');
      }
      // outputs 'bigger', not smaller as expected

      The contents of the if statement is an arrow function, not a comparison.

      If the arrow function is intentional, it should be wrapped in parens to remove ambiguity.

      /*eslint-env es6*/
      
      var a = 1;
      var b = 0;
      // ...
      if ((a) => b) {
       console.log('truthy value returned');
      } else {
       console.log('falsey value returned');
      }
      // outputs 'truthy value returned'

      The following is another example of this behavior:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = a => b ? c: d;
      // f = ?

      f is an arrow function which takes a as an argument and returns the result of b ? c: d.

      This should be rewritten like so:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = (a) => b ? c: d;

      as-needed

      Examples of incorrect code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => a;
      (a) => {'\n'};
      a.then((foo) => {});
      a.then((foo) => a);
      a((foo) => { if (true) {} });

      Examples of correct code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      () => {};
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      requireForBlockBody

      Examples of incorrect code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => a;
      a => {};
      a => {'\n'};
      a.map((x) => x * x);
      a.map(x => {
        return x * x;
      });
      a.then(foo => {});

      Examples of correct code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => {'\n'};
      a => ({});
      () => {};
      a => a;
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });
      a((foo) => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      Further Reading

      Unexpected parentheses around single function argument having a body with no curly braces
      Open

                  text: (arg) => arg.$scope.text(),
      Severity: Minor
      Found in test/example.md.js by eslint

      Require parens in arrow function arguments (arrow-parens)

      Arrow functions can omit parentheses when they have exactly one parameter. In all other cases the parameter(s) must be wrapped in parentheses. This rule enforces the consistent use of parentheses in arrow functions.

      Rule Details

      This rule enforces parentheses around arrow function parameters regardless of arity. For example:

      /*eslint-env es6*/
      
      // Bad
      a => {}
      
      // Good
      (a) => {}

      Following this style will help you find arrow functions (=>) which may be mistakenly included in a condition when a comparison such as >= was the intent.

      /*eslint-env es6*/
      
      // Bad
      if (a => 2) {
      }
      
      // Good
      if (a >= 2) {
      }

      The rule can also be configured to discourage the use of parens when they are not required:

      /*eslint-env es6*/
      
      // Bad
      (a) => {}
      
      // Good
      a => {}

      Options

      This rule has a string option and an object one.

      String options are:

      • "always" (default) requires parens around arguments in all cases.
      • "as-needed" allows omitting parens when there is only one argument.

      Object properties for variants of the "as-needed" option:

      • "requireForBlockBody": true modifies the as-needed rule in order to require parens if the function body is in an instructions block (surrounded by braces).

      always

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => a);
      a(foo => { if (true) {} });

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      () => {};
      (a) => {};
      (a) => a;
      (a) => {'\n'}
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });

      If Statements

      One of benefits of this option is that it prevents the incorrect use of arrow functions in conditionals:

      /*eslint-env es6*/
      
      var a = 1;
      var b = 2;
      // ...
      if (a => b) {
       console.log('bigger');
      } else {
       console.log('smaller');
      }
      // outputs 'bigger', not smaller as expected

      The contents of the if statement is an arrow function, not a comparison.

      If the arrow function is intentional, it should be wrapped in parens to remove ambiguity.

      /*eslint-env es6*/
      
      var a = 1;
      var b = 0;
      // ...
      if ((a) => b) {
       console.log('truthy value returned');
      } else {
       console.log('falsey value returned');
      }
      // outputs 'truthy value returned'

      The following is another example of this behavior:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = a => b ? c: d;
      // f = ?

      f is an arrow function which takes a as an argument and returns the result of b ? c: d.

      This should be rewritten like so:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = (a) => b ? c: d;

      as-needed

      Examples of incorrect code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => a;
      (a) => {'\n'};
      a.then((foo) => {});
      a.then((foo) => a);
      a((foo) => { if (true) {} });

      Examples of correct code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      () => {};
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      requireForBlockBody

      Examples of incorrect code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => a;
      a => {};
      a => {'\n'};
      a.map((x) => x * x);
      a.map(x => {
        return x * x;
      });
      a.then(foo => {});

      Examples of correct code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => {'\n'};
      a => ({});
      () => {};
      a => a;
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });
      a((foo) => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      Further Reading

      Unexpected parentheses around single function argument having a body with no curly braces
      Open

                      src: (arg) => arg.$scope.attr('src'),
      Severity: Minor
      Found in test/example.md.js by eslint

      Require parens in arrow function arguments (arrow-parens)

      Arrow functions can omit parentheses when they have exactly one parameter. In all other cases the parameter(s) must be wrapped in parentheses. This rule enforces the consistent use of parentheses in arrow functions.

      Rule Details

      This rule enforces parentheses around arrow function parameters regardless of arity. For example:

      /*eslint-env es6*/
      
      // Bad
      a => {}
      
      // Good
      (a) => {}

      Following this style will help you find arrow functions (=>) which may be mistakenly included in a condition when a comparison such as >= was the intent.

      /*eslint-env es6*/
      
      // Bad
      if (a => 2) {
      }
      
      // Good
      if (a >= 2) {
      }

      The rule can also be configured to discourage the use of parens when they are not required:

      /*eslint-env es6*/
      
      // Bad
      (a) => {}
      
      // Good
      a => {}

      Options

      This rule has a string option and an object one.

      String options are:

      • "always" (default) requires parens around arguments in all cases.
      • "as-needed" allows omitting parens when there is only one argument.

      Object properties for variants of the "as-needed" option:

      • "requireForBlockBody": true modifies the as-needed rule in order to require parens if the function body is in an instructions block (surrounded by braces).

      always

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => a);
      a(foo => { if (true) {} });

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      () => {};
      (a) => {};
      (a) => a;
      (a) => {'\n'}
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });

      If Statements

      One of benefits of this option is that it prevents the incorrect use of arrow functions in conditionals:

      /*eslint-env es6*/
      
      var a = 1;
      var b = 2;
      // ...
      if (a => b) {
       console.log('bigger');
      } else {
       console.log('smaller');
      }
      // outputs 'bigger', not smaller as expected

      The contents of the if statement is an arrow function, not a comparison.

      If the arrow function is intentional, it should be wrapped in parens to remove ambiguity.

      /*eslint-env es6*/
      
      var a = 1;
      var b = 0;
      // ...
      if ((a) => b) {
       console.log('truthy value returned');
      } else {
       console.log('falsey value returned');
      }
      // outputs 'truthy value returned'

      The following is another example of this behavior:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = a => b ? c: d;
      // f = ?

      f is an arrow function which takes a as an argument and returns the result of b ? c: d.

      This should be rewritten like so:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = (a) => b ? c: d;

      as-needed

      Examples of incorrect code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => a;
      (a) => {'\n'};
      a.then((foo) => {});
      a.then((foo) => a);
      a((foo) => { if (true) {} });

      Examples of correct code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      () => {};
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      requireForBlockBody

      Examples of incorrect code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => a;
      a => {};
      a => {'\n'};
      a.map((x) => x * x);
      a.map(x => {
        return x * x;
      });
      a.then(foo => {});

      Examples of correct code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => {'\n'};
      a => ({});
      () => {};
      a => a;
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });
      a((foo) => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      Further Reading

      Unexpected parentheses around single function argument having a body with no curly braces
      Open

                          return paragraphs.map((p) => arg.$(p).text());
      Severity: Minor
      Found in test/test.js by eslint

      Require parens in arrow function arguments (arrow-parens)

      Arrow functions can omit parentheses when they have exactly one parameter. In all other cases the parameter(s) must be wrapped in parentheses. This rule enforces the consistent use of parentheses in arrow functions.

      Rule Details

      This rule enforces parentheses around arrow function parameters regardless of arity. For example:

      /*eslint-env es6*/
      
      // Bad
      a => {}
      
      // Good
      (a) => {}

      Following this style will help you find arrow functions (=>) which may be mistakenly included in a condition when a comparison such as >= was the intent.

      /*eslint-env es6*/
      
      // Bad
      if (a => 2) {
      }
      
      // Good
      if (a >= 2) {
      }

      The rule can also be configured to discourage the use of parens when they are not required:

      /*eslint-env es6*/
      
      // Bad
      (a) => {}
      
      // Good
      a => {}

      Options

      This rule has a string option and an object one.

      String options are:

      • "always" (default) requires parens around arguments in all cases.
      • "as-needed" allows omitting parens when there is only one argument.

      Object properties for variants of the "as-needed" option:

      • "requireForBlockBody": true modifies the as-needed rule in order to require parens if the function body is in an instructions block (surrounded by braces).

      always

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => a);
      a(foo => { if (true) {} });

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      () => {};
      (a) => {};
      (a) => a;
      (a) => {'\n'}
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });

      If Statements

      One of benefits of this option is that it prevents the incorrect use of arrow functions in conditionals:

      /*eslint-env es6*/
      
      var a = 1;
      var b = 2;
      // ...
      if (a => b) {
       console.log('bigger');
      } else {
       console.log('smaller');
      }
      // outputs 'bigger', not smaller as expected

      The contents of the if statement is an arrow function, not a comparison.

      If the arrow function is intentional, it should be wrapped in parens to remove ambiguity.

      /*eslint-env es6*/
      
      var a = 1;
      var b = 0;
      // ...
      if ((a) => b) {
       console.log('truthy value returned');
      } else {
       console.log('falsey value returned');
      }
      // outputs 'truthy value returned'

      The following is another example of this behavior:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = a => b ? c: d;
      // f = ?

      f is an arrow function which takes a as an argument and returns the result of b ? c: d.

      This should be rewritten like so:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = (a) => b ? c: d;

      as-needed

      Examples of incorrect code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => a;
      (a) => {'\n'};
      a.then((foo) => {});
      a.then((foo) => a);
      a((foo) => { if (true) {} });

      Examples of correct code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      () => {};
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      requireForBlockBody

      Examples of incorrect code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => a;
      a => {};
      a => {'\n'};
      a.map((x) => x * x);
      a.map(x => {
        return x * x;
      });
      a.then(foo => {});

      Examples of correct code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => {'\n'};
      a => ({});
      () => {};
      a => a;
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });
      a((foo) => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      Further Reading

      Unexpected parentheses around single function argument having a body with no curly braces
      Open

                  const actual = htmlMiner(html, (arg) => arg.$('.title').text());
      Severity: Minor
      Found in test/readme.md.js by eslint

      Require parens in arrow function arguments (arrow-parens)

      Arrow functions can omit parentheses when they have exactly one parameter. In all other cases the parameter(s) must be wrapped in parentheses. This rule enforces the consistent use of parentheses in arrow functions.

      Rule Details

      This rule enforces parentheses around arrow function parameters regardless of arity. For example:

      /*eslint-env es6*/
      
      // Bad
      a => {}
      
      // Good
      (a) => {}

      Following this style will help you find arrow functions (=>) which may be mistakenly included in a condition when a comparison such as >= was the intent.

      /*eslint-env es6*/
      
      // Bad
      if (a => 2) {
      }
      
      // Good
      if (a >= 2) {
      }

      The rule can also be configured to discourage the use of parens when they are not required:

      /*eslint-env es6*/
      
      // Bad
      (a) => {}
      
      // Good
      a => {}

      Options

      This rule has a string option and an object one.

      String options are:

      • "always" (default) requires parens around arguments in all cases.
      • "as-needed" allows omitting parens when there is only one argument.

      Object properties for variants of the "as-needed" option:

      • "requireForBlockBody": true modifies the as-needed rule in order to require parens if the function body is in an instructions block (surrounded by braces).

      always

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => a);
      a(foo => { if (true) {} });

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      () => {};
      (a) => {};
      (a) => a;
      (a) => {'\n'}
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });

      If Statements

      One of benefits of this option is that it prevents the incorrect use of arrow functions in conditionals:

      /*eslint-env es6*/
      
      var a = 1;
      var b = 2;
      // ...
      if (a => b) {
       console.log('bigger');
      } else {
       console.log('smaller');
      }
      // outputs 'bigger', not smaller as expected

      The contents of the if statement is an arrow function, not a comparison.

      If the arrow function is intentional, it should be wrapped in parens to remove ambiguity.

      /*eslint-env es6*/
      
      var a = 1;
      var b = 0;
      // ...
      if ((a) => b) {
       console.log('truthy value returned');
      } else {
       console.log('falsey value returned');
      }
      // outputs 'truthy value returned'

      The following is another example of this behavior:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = a => b ? c: d;
      // f = ?

      f is an arrow function which takes a as an argument and returns the result of b ? c: d.

      This should be rewritten like so:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = (a) => b ? c: d;

      as-needed

      Examples of incorrect code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => a;
      (a) => {'\n'};
      a.then((foo) => {});
      a.then((foo) => a);
      a((foo) => { if (true) {} });

      Examples of correct code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      () => {};
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      requireForBlockBody

      Examples of incorrect code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => a;
      a => {};
      a => {'\n'};
      a.map((x) => x * x);
      a.map(x => {
        return x * x;
      });
      a.then(foo => {});

      Examples of correct code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => {'\n'};
      a => ({});
      () => {};
      a => a;
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });
      a((foo) => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      Further Reading

      Unexpected parentheses around single function argument having a body with no curly braces
      Open

                      alt: (arg) => arg.$scope.attr('alt'),
      Severity: Minor
      Found in test/example.md.js by eslint

      Require parens in arrow function arguments (arrow-parens)

      Arrow functions can omit parentheses when they have exactly one parameter. In all other cases the parameter(s) must be wrapped in parentheses. This rule enforces the consistent use of parentheses in arrow functions.

      Rule Details

      This rule enforces parentheses around arrow function parameters regardless of arity. For example:

      /*eslint-env es6*/
      
      // Bad
      a => {}
      
      // Good
      (a) => {}

      Following this style will help you find arrow functions (=>) which may be mistakenly included in a condition when a comparison such as >= was the intent.

      /*eslint-env es6*/
      
      // Bad
      if (a => 2) {
      }
      
      // Good
      if (a >= 2) {
      }

      The rule can also be configured to discourage the use of parens when they are not required:

      /*eslint-env es6*/
      
      // Bad
      (a) => {}
      
      // Good
      a => {}

      Options

      This rule has a string option and an object one.

      String options are:

      • "always" (default) requires parens around arguments in all cases.
      • "as-needed" allows omitting parens when there is only one argument.

      Object properties for variants of the "as-needed" option:

      • "requireForBlockBody": true modifies the as-needed rule in order to require parens if the function body is in an instructions block (surrounded by braces).

      always

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => a);
      a(foo => { if (true) {} });

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      () => {};
      (a) => {};
      (a) => a;
      (a) => {'\n'}
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });

      If Statements

      One of benefits of this option is that it prevents the incorrect use of arrow functions in conditionals:

      /*eslint-env es6*/
      
      var a = 1;
      var b = 2;
      // ...
      if (a => b) {
       console.log('bigger');
      } else {
       console.log('smaller');
      }
      // outputs 'bigger', not smaller as expected

      The contents of the if statement is an arrow function, not a comparison.

      If the arrow function is intentional, it should be wrapped in parens to remove ambiguity.

      /*eslint-env es6*/
      
      var a = 1;
      var b = 0;
      // ...
      if ((a) => b) {
       console.log('truthy value returned');
      } else {
       console.log('falsey value returned');
      }
      // outputs 'truthy value returned'

      The following is another example of this behavior:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = a => b ? c: d;
      // f = ?

      f is an arrow function which takes a as an argument and returns the result of b ? c: d.

      This should be rewritten like so:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = (a) => b ? c: d;

      as-needed

      Examples of incorrect code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => a;
      (a) => {'\n'};
      a.then((foo) => {});
      a.then((foo) => a);
      a((foo) => { if (true) {} });

      Examples of correct code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      () => {};
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      requireForBlockBody

      Examples of incorrect code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => a;
      a => {};
      a => {'\n'};
      a.map((x) => x * x);
      a.map(x => {
        return x * x;
      });
      a.then(foo => {});

      Examples of correct code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => {'\n'};
      a => ({});
      () => {};
      a => a;
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });
      a((foo) => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      Further Reading

      Unexpected parentheses around single function argument having a body with no curly braces
      Open

                  href: (arg) => arg.$scope.attr('href'),
      Severity: Minor
      Found in test/example.md.js by eslint

      Require parens in arrow function arguments (arrow-parens)

      Arrow functions can omit parentheses when they have exactly one parameter. In all other cases the parameter(s) must be wrapped in parentheses. This rule enforces the consistent use of parentheses in arrow functions.

      Rule Details

      This rule enforces parentheses around arrow function parameters regardless of arity. For example:

      /*eslint-env es6*/
      
      // Bad
      a => {}
      
      // Good
      (a) => {}

      Following this style will help you find arrow functions (=>) which may be mistakenly included in a condition when a comparison such as >= was the intent.

      /*eslint-env es6*/
      
      // Bad
      if (a => 2) {
      }
      
      // Good
      if (a >= 2) {
      }

      The rule can also be configured to discourage the use of parens when they are not required:

      /*eslint-env es6*/
      
      // Bad
      (a) => {}
      
      // Good
      a => {}

      Options

      This rule has a string option and an object one.

      String options are:

      • "always" (default) requires parens around arguments in all cases.
      • "as-needed" allows omitting parens when there is only one argument.

      Object properties for variants of the "as-needed" option:

      • "requireForBlockBody": true modifies the as-needed rule in order to require parens if the function body is in an instructions block (surrounded by braces).

      always

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => a);
      a(foo => { if (true) {} });

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

      /*eslint arrow-parens: ["error", "always"]*/
      /*eslint-env es6*/
      
      () => {};
      (a) => {};
      (a) => a;
      (a) => {'\n'}
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });

      If Statements

      One of benefits of this option is that it prevents the incorrect use of arrow functions in conditionals:

      /*eslint-env es6*/
      
      var a = 1;
      var b = 2;
      // ...
      if (a => b) {
       console.log('bigger');
      } else {
       console.log('smaller');
      }
      // outputs 'bigger', not smaller as expected

      The contents of the if statement is an arrow function, not a comparison.

      If the arrow function is intentional, it should be wrapped in parens to remove ambiguity.

      /*eslint-env es6*/
      
      var a = 1;
      var b = 0;
      // ...
      if ((a) => b) {
       console.log('truthy value returned');
      } else {
       console.log('falsey value returned');
      }
      // outputs 'truthy value returned'

      The following is another example of this behavior:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = a => b ? c: d;
      // f = ?

      f is an arrow function which takes a as an argument and returns the result of b ? c: d.

      This should be rewritten like so:

      /*eslint-env es6*/
      
      var a = 1, b = 2, c = 3, d = 4;
      var f = (a) => b ? c: d;

      as-needed

      Examples of incorrect code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => a;
      (a) => {'\n'};
      a.then((foo) => {});
      a.then((foo) => a);
      a((foo) => { if (true) {} });

      Examples of correct code for this rule with the "as-needed" option:

      /*eslint arrow-parens: ["error", "as-needed"]*/
      /*eslint-env es6*/
      
      () => {};
      a => {};
      a => a;
      a => {'\n'};
      a.then(foo => {});
      a.then(foo => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      requireForBlockBody

      Examples of incorrect code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => a;
      a => {};
      a => {'\n'};
      a.map((x) => x * x);
      a.map(x => {
        return x * x;
      });
      a.then(foo => {});

      Examples of correct code for the { "requireForBlockBody": true } option:

      /*eslint arrow-parens: [2, "as-needed", { "requireForBlockBody": true }]*/
      /*eslint-env es6*/
      
      (a) => {};
      (a) => {'\n'};
      a => ({});
      () => {};
      a => a;
      a.then((foo) => {});
      a.then((foo) => { if (true) {} });
      a((foo) => { if (true) {} });
      (a, b, c) => a;
      (a = 10) => a;
      ([a, b]) => a;
      ({a, b}) => a;

      Further Reading

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      Category
      Status
      Source
      Language