prefer-as-const

Enforce the use of as const over literal type.

This rule recommends usage of const assertion when type primitive value is equal to type.

Attributes

• Included in configs
  • ✅ Recommended
  • 🔒 Strict
• Fixable
  • 🔧 Automated Fixer
  • 🛠 Suggestion Fixer
• 💭 Requires type information

Rule Details

Examples of code for this rule:

❌ Incorrect

let bar: 2 = 2;
let foo = <'bar'>'bar';
let foo = { bar: 'baz' as 'baz' };

✅ Correct

let foo = 'bar';
let foo = 'bar' as const;
let foo: 'bar' = 'bar' as const;
let bar = 'bar' as string;
let foo = <string>'bar';
let foo = { bar: 'baz' };

Options

// .eslintrc.json
{
  "rules": {
    "@typescript-eslint/prefer-as-const": "error"
  }
}

This rule is not configurable.

When Not To Use It

If you are using TypeScript < 3.4