# @typescript-eslint/prefer-as-const

> 来自 [plugin:@typescript-eslint/recommended](https://www.npmjs.com/package/@typescript-eslint/eslint-plugin) 的规则。

# Prefer usage of `as const` over literal type (`prefer-as-const`)

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

## Rule Details

Examples of **incorrect** code for this rule:

```ts
let bar: 2 = 2;
let foo = <"bar">"bar";
let foo = { bar: "baz" as "baz" };
```

Examples of **correct** code for this rule:

```ts
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" };
```

## When Not To Use It

If you are using TypeScript < 3.4

## 参考文档

- [@typescript-eslint/prefer-as-const 官方文档](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/docs/rules/prefer-as-const.md)