JS.TS.PREFER.ENUM.INITIALIZERS

Prefer initializing each enums member value

This rule recommends having each enums member value explicitly initialized.

enums are a practical way to organize semantically related constant values. However, by implicitly defining values, enums can lead to unexpected bugs if it's modified without paying attention to the order of its items.

Rule Details

enums infers sequential numbers automatically when initializers are omitted:

コピー

enum Status {
  Open, // infer 0
  Closed, // infer 1
}

If a new member is added to the top of Status, both Open and Closed would have its values altered:

コピー

enum Status {
  Pending, // infer 0
  Open, // infer 1
  Closed, // infer 2
}

Examples of code for this rule:

Incorrect

コピー

enum Status {
  Open = 1,
  Close,
}

enum Direction {
  Up,
  Down,
}

enum Color {
  Red,
  Green = 'Green'
  Blue = 'Blue',
}

Correct

コピー

enum Status {
  Open = 'Open',
  Close = 'Close',
}

enum Direction {
  Up = 1,
  Down = 2,
}

enum Color {
  Red = 'Red',
  Green = 'Green',
  Blue = 'Blue',
}

Options

コピー

// .eslintrc.json
{
  "rules": {
    "@typescript-eslint/prefer-enum-initializers": "warn"
  }
}

This rule is not configurable.

When Not To Use It

If you don't care about enums having implicit values you can safely disable this rule.