prefer-as-const

Enforce the use of as const over literal type.

✅

在 ESLint 配置中扩展"plugin:@typescript-eslint/recommended" 可启用此规则。

🔧

此规则报告的一些问题可通过 --fix ESLint 命令行选项自动修复。

💡

此规则报告的一些问题可以通过编辑器建议手动修复。

有两种常用方法可以告诉 TypeScript，文字值应该解释为其文字类型（例如 2），而不是一般的原始类型（例如 number）；

¥There are two common ways to tell TypeScript that a literal value should be interpreted as its literal type (e.g. 2) rather than general primitive type (e.g. number);

as const：告诉 TypeScript 自动推断字面量类型

¥as const: telling TypeScript to infer the literal type automatically
as 带有文字类型：明确地告诉 TypeScript 字面量类型

¥as with the literal type: explicitly telling the literal type to TypeScript

as const 通常是首选，因为它不需要重新输入文字值。此规则报告何时可以使用 as const 替换具有显式文字类型的 as。

¥as const is generally preferred, as it doesn't require re-typing the literal value. This rule reports when an as with an explicit literal type can be replaced with an as const.

Flat Config
Legacy Config

eslint.config.mjs
export default tseslint.config({
  rules: {
    "@typescript-eslint/prefer-as-const": "error"
  }
});

.eslintrc.cjs
module.exports = {
  "rules": {
    "@typescript-eslint/prefer-as-const": "error"
  }
};

在线运行试试这个规则 ↗

示例

¥Examples

❌ Incorrect
✅ Correct

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

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' };
Open in Playground

选项

该规则不可配置。

何时不使用它

¥When Not To Use It

如果你不关心代码中使用哪种样式的字面量断言，那么你将不需要此规则。

¥If you don't care about which style of literals assertions is used in your code, then you will not need this rule.

但是，请记住，不一致的风格可能会损害项目的可读性。我们建议为此规则选择一个最适合你的项目的选项。

¥However, keep in mind that inconsistent style can harm readability in a project. We recommend picking a single option for this rule that works best for your project.

'## 资源'

示例​

选项​

何时不使用它​

示例

选项

何时不使用它