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

• Extract Method
• Extract Class
• Form Template Method
• Introduce Null Object
• Pull Up Method
• Pull Up Field
• Substitute Algorithm

Further Reading

• Don't Repeat Yourself on the C2 Wiki
• Duplicated Code on SourceMaking
• Refactoring: Improving the Design of Existing Code by Martin Fowler. Duplicated Code, p76

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

• Extract Method
• Extract Class
• Form Template Method
• Introduce Null Object
• Pull Up Method
• Pull Up Field
• Substitute Algorithm

Further Reading

• Don't Repeat Yourself on the C2 Wiki
• Duplicated Code on SourceMaking
• Refactoring: Improving the Design of Existing Code by Martin Fowler. Duplicated Code, p76

Rule: quotemark

Enforces quote character for string literals.

Notes

• Has Fix

Config

Five arguments may be optionally provided:

• "single" enforces single quotes.
• "double" enforces double quotes.
• "backtick" enforces backticks.
• "jsx-single" enforces single quotes for JSX attributes.
• "jsx-double" enforces double quotes for JSX attributes.
• "avoid-template" forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if "avoid-escape" is enabled and both single and double quotes are present in the string (the latter option takes precedence).
• "avoid-escape" allows you to use the "other" quotemark in cases where escaping would normally be required. For example, [true, "double", "avoid-escape"] would not report a failure on the string literal 'Hello "World"'.

Examples

"quotemark": true,single,avoid-escape,avoid-template

"quotemark": true,single,jsx-double

Schema

{
  "type": "array",
  "items": {
    "type": "string",
    "enum": [
      "single",
      "double",
      "backtick",
      "jsx-single",
      "jsx-double",
      "avoid-escape",
      "avoid-template"
    ]
  },
  "minLength": 0,
  "maxLength": 5
}

For more information see this page.

Rule: ban-types

Bans specific types from being used. Does not ban the corresponding runtime objects from being used.

Notes

• TypeScript Only

Config

A list of ["regex", "optional explanation here"], which bans types that match regex

Examples

"ban-types": true,Object,Use {} instead.,String

Schema

{
  "type": "list",
  "listType": {
    "type": "array",
    "items": {
      "type": "string"
    },
    "minLength": 1,
    "maxLength": 2
  }
}

For more information see this page.

Rule: quotemark

Enforces quote character for string literals.

Notes

• Has Fix

Config

Five arguments may be optionally provided:

• "single" enforces single quotes.
• "double" enforces double quotes.
• "backtick" enforces backticks.
• "jsx-single" enforces single quotes for JSX attributes.
• "jsx-double" enforces double quotes for JSX attributes.
• "avoid-template" forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if "avoid-escape" is enabled and both single and double quotes are present in the string (the latter option takes precedence).
• "avoid-escape" allows you to use the "other" quotemark in cases where escaping would normally be required. For example, [true, "double", "avoid-escape"] would not report a failure on the string literal 'Hello "World"'.

Examples

"quotemark": true,single,avoid-escape,avoid-template

"quotemark": true,single,jsx-double

Schema

{
  "type": "array",
  "items": {
    "type": "string",
    "enum": [
      "single",
      "double",
      "backtick",
      "jsx-single",
      "jsx-double",
      "avoid-escape",
      "avoid-template"
    ]
  },
  "minLength": 0,
  "maxLength": 5
}

For more information see this page.

Rule: quotemark

Enforces quote character for string literals.

Notes

• Has Fix

Config

Five arguments may be optionally provided:

• "single" enforces single quotes.
• "double" enforces double quotes.
• "backtick" enforces backticks.
• "jsx-single" enforces single quotes for JSX attributes.
• "jsx-double" enforces double quotes for JSX attributes.
• "avoid-template" forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if "avoid-escape" is enabled and both single and double quotes are present in the string (the latter option takes precedence).
• "avoid-escape" allows you to use the "other" quotemark in cases where escaping would normally be required. For example, [true, "double", "avoid-escape"] would not report a failure on the string literal 'Hello "World"'.

Examples

"quotemark": true,single,avoid-escape,avoid-template

"quotemark": true,single,jsx-double

Schema

{
  "type": "array",
  "items": {
    "type": "string",
    "enum": [
      "single",
      "double",
      "backtick",
      "jsx-single",
      "jsx-double",
      "avoid-escape",
      "avoid-template"
    ]
  },
  "minLength": 0,
  "maxLength": 5
}

For more information see this page.

Rule: no-empty

Disallows empty blocks.

Blocks with a comment inside are not considered empty.

Rationale

Empty blocks are often indicators of missing code.

Config

If allow-empty-catch is specified, then catch blocks are allowed to be empty. If allow-empty-functions is specified, then function definitions are allowed to be empty.

Examples

"no-empty": true

"no-empty": true,allow-empty-catch

"no-empty": true,allow-empty-functions

"no-empty": true,allow-empty-catch,allow-empty-functions

Schema

{
  "type": "array",
  "items": {
    "anyOf": [
      {
        "type": "string",
        "enum": [
          "allow-empty-catch"
        ]
      },
      {
        "type": "string",
        "enum": [
          "allow-empty-functions"
        ]
      }
    ]
  }
}

For more information see this page.

Rule: quotemark

Enforces quote character for string literals.

Notes

• Has Fix

Config

Five arguments may be optionally provided:

• "single" enforces single quotes.
• "double" enforces double quotes.
• "backtick" enforces backticks.
• "jsx-single" enforces single quotes for JSX attributes.
• "jsx-double" enforces double quotes for JSX attributes.
• "avoid-template" forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if "avoid-escape" is enabled and both single and double quotes are present in the string (the latter option takes precedence).
• "avoid-escape" allows you to use the "other" quotemark in cases where escaping would normally be required. For example, [true, "double", "avoid-escape"] would not report a failure on the string literal 'Hello "World"'.

Examples

"quotemark": true,single,avoid-escape,avoid-template

"quotemark": true,single,jsx-double

Schema

{
  "type": "array",
  "items": {
    "type": "string",
    "enum": [
      "single",
      "double",
      "backtick",
      "jsx-single",
      "jsx-double",
      "avoid-escape",
      "avoid-template"
    ]
  },
  "minLength": 0,
  "maxLength": 5
}

For more information see this page.

Rule: quotemark

Enforces quote character for string literals.

Notes

• Has Fix

Config

Five arguments may be optionally provided:

• "single" enforces single quotes.
• "double" enforces double quotes.
• "backtick" enforces backticks.
• "jsx-single" enforces single quotes for JSX attributes.
• "jsx-double" enforces double quotes for JSX attributes.
• "avoid-template" forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if "avoid-escape" is enabled and both single and double quotes are present in the string (the latter option takes precedence).
• "avoid-escape" allows you to use the "other" quotemark in cases where escaping would normally be required. For example, [true, "double", "avoid-escape"] would not report a failure on the string literal 'Hello "World"'.

Examples

"quotemark": true,single,avoid-escape,avoid-template

"quotemark": true,single,jsx-double

Schema

{
  "type": "array",
  "items": {
    "type": "string",
    "enum": [
      "single",
      "double",
      "backtick",
      "jsx-single",
      "jsx-double",
      "avoid-escape",
      "avoid-template"
    ]
  },
  "minLength": 0,
  "maxLength": 5
}

For more information see this page.

Rule: quotemark

Enforces quote character for string literals.

Notes

• Has Fix

Config

Five arguments may be optionally provided:

• "single" enforces single quotes.
• "double" enforces double quotes.
• "backtick" enforces backticks.
• "jsx-single" enforces single quotes for JSX attributes.
• "jsx-double" enforces double quotes for JSX attributes.
• "avoid-template" forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if "avoid-escape" is enabled and both single and double quotes are present in the string (the latter option takes precedence).
• "avoid-escape" allows you to use the "other" quotemark in cases where escaping would normally be required. For example, [true, "double", "avoid-escape"] would not report a failure on the string literal 'Hello "World"'.

Examples

"quotemark": true,single,avoid-escape,avoid-template

"quotemark": true,single,jsx-double

Schema

{
  "type": "array",
  "items": {
    "type": "string",
    "enum": [
      "single",
      "double",
      "backtick",
      "jsx-single",
      "jsx-double",
      "avoid-escape",
      "avoid-template"
    ]
  },
  "minLength": 0,
  "maxLength": 5
}

For more information see this page.

Rule: no-this-assignment

Disallows unnecessary references to this.

Rationale

Assigning a variable to this instead of properly using arrow lambdas may be a symptom of pre-ES6 practices or not managing scope well.

Instead of storing a reference to this and using it inside a function () {:

const self = this;

setTimeout(function () {
    self.doWork();
});

Use () => arrow lambdas, as they preserve this scope for you:

setTimeout(() => {
    this.doWork();
});

Config

Two options may be provided on an object:

• allow-destructuring allows using destructuring to access members of this (e.g. { foo, bar } = this;).
• allowed-names may be specified as a list of regular expressions to match allowed variable names.

Examples

"no-this-assignment": true

"no-this-assignment": true,[object Object]

Schema

{
  "additionalProperties": false,
  "properties": {
    "allow-destructuring": {
      "type": "boolean"
    },
    "allowed-names": {
      "listType": "string",
      "type": "list"
    }
  },
  "type": "object"
}

For more information see this page.

Rule: quotemark

Enforces quote character for string literals.

Notes

• Has Fix

Config

Five arguments may be optionally provided:

• "single" enforces single quotes.
• "double" enforces double quotes.
• "backtick" enforces backticks.
• "jsx-single" enforces single quotes for JSX attributes.
• "jsx-double" enforces double quotes for JSX attributes.
• "avoid-template" forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if "avoid-escape" is enabled and both single and double quotes are present in the string (the latter option takes precedence).
• "avoid-escape" allows you to use the "other" quotemark in cases where escaping would normally be required. For example, [true, "double", "avoid-escape"] would not report a failure on the string literal 'Hello "World"'.

Examples

"quotemark": true,single,avoid-escape,avoid-template

"quotemark": true,single,jsx-double

Schema

{
  "type": "array",
  "items": {
    "type": "string",
    "enum": [
      "single",
      "double",
      "backtick",
      "jsx-single",
      "jsx-double",
      "avoid-escape",
      "avoid-template"
    ]
  },
  "minLength": 0,
  "maxLength": 5
}

For more information see this page.

Rule: quotemark

Enforces quote character for string literals.

Notes

• Has Fix

Config

Five arguments may be optionally provided:

• "single" enforces single quotes.
• "double" enforces double quotes.
• "backtick" enforces backticks.
• "jsx-single" enforces single quotes for JSX attributes.
• "jsx-double" enforces double quotes for JSX attributes.
• "avoid-template" forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if "avoid-escape" is enabled and both single and double quotes are present in the string (the latter option takes precedence).
• "avoid-escape" allows you to use the "other" quotemark in cases where escaping would normally be required. For example, [true, "double", "avoid-escape"] would not report a failure on the string literal 'Hello "World"'.

Examples

"quotemark": true,single,avoid-escape,avoid-template

"quotemark": true,single,jsx-double

Schema

{
  "type": "array",
  "items": {
    "type": "string",
    "enum": [
      "single",
      "double",
      "backtick",
      "jsx-single",
      "jsx-double",
      "avoid-escape",
      "avoid-template"
    ]
  },
  "minLength": 0,
  "maxLength": 5
}

For more information see this page.

Rule: quotemark

Enforces quote character for string literals.

Notes

• Has Fix

Config

Five arguments may be optionally provided:

• "single" enforces single quotes.
• "double" enforces double quotes.
• "backtick" enforces backticks.
• "jsx-single" enforces single quotes for JSX attributes.
• "jsx-double" enforces double quotes for JSX attributes.
• "avoid-template" forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if "avoid-escape" is enabled and both single and double quotes are present in the string (the latter option takes precedence).
• "avoid-escape" allows you to use the "other" quotemark in cases where escaping would normally be required. For example, [true, "double", "avoid-escape"] would not report a failure on the string literal 'Hello "World"'.

Examples

"quotemark": true,single,avoid-escape,avoid-template

"quotemark": true,single,jsx-double

Schema

{
  "type": "array",
  "items": {
    "type": "string",
    "enum": [
      "single",
      "double",
      "backtick",
      "jsx-single",
      "jsx-double",
      "avoid-escape",
      "avoid-template"
    ]
  },
  "minLength": 0,
  "maxLength": 5
}

For more information see this page.

Rule: quotemark

Enforces quote character for string literals.

Notes

• Has Fix

Config

Five arguments may be optionally provided:

• "single" enforces single quotes.
• "double" enforces double quotes.
• "backtick" enforces backticks.
• "jsx-single" enforces single quotes for JSX attributes.
• "jsx-double" enforces double quotes for JSX attributes.
• "avoid-template" forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if "avoid-escape" is enabled and both single and double quotes are present in the string (the latter option takes precedence).
• "avoid-escape" allows you to use the "other" quotemark in cases where escaping would normally be required. For example, [true, "double", "avoid-escape"] would not report a failure on the string literal 'Hello "World"'.

Examples

"quotemark": true,single,avoid-escape,avoid-template

"quotemark": true,single,jsx-double

Schema

{
  "type": "array",
  "items": {
    "type": "string",
    "enum": [
      "single",
      "double",
      "backtick",
      "jsx-single",
      "jsx-double",
      "avoid-escape",
      "avoid-template"
    ]
  },
  "minLength": 0,
  "maxLength": 5
}

For more information see this page.