# @typescript-eslint/no-non-null-assertion

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

# Disallows non-null assertions using the `!` postfix operator (`no-non-null-assertion`)

## Rule Details

Using non-null assertions cancels the benefits of the strict null-checking mode.

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

```ts
interface Foo {
  bar?: string;
}

const foo: Foo = getFoo();
const includesBaz: boolean = foo.bar!.includes("baz");
```

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

```ts
interface Foo {
  bar?: string;
}

const foo: Foo = getFoo();
const includesBaz: boolean = foo.bar?.includes("baz") ?? false;
```

## When Not To Use It

If you don't care about strict null-checking, then you will not need this rule.

## Further Reading

- [`no-non-null-assertion`](https://palantir.github.io/tslint/rules/no-non-null-assertion/) in [TSLint](https://palantir.github.io/tslint/)

## 参考文档

- [@typescript-eslint/no-non-null-assertion 官方文档](https://github.com/typescript-eslint/typescript-eslint/blob/HEAD/packages/eslint-plugin/docs/rules/no-non-null-assertion.md)