mirror of
https://github.com/Sevichecc/Urara-Blog.git
synced 2025-05-02 23:09:30 +08:00
72 lines
1.6 KiB
Text
72 lines
1.6 KiB
Text
---
|
|
description: 'Disallow non-null assertions in the left operand of a nullish coalescing operator.'
|
|
---
|
|
|
|
> 🛑 This file is source code, not the primary documentation location! 🛑
|
|
>
|
|
> See **https://typescript-eslint.io/rules/no-non-null-asserted-nullish-coalescing** for documentation.
|
|
|
|
## Rule Details
|
|
|
|
The nullish coalescing operator is designed to provide a default value when dealing with `null` or `undefined`.
|
|
Using non-null assertions in the left operand of the nullish coalescing operator is redundant.
|
|
|
|
Examples of code for this rule:
|
|
|
|
<!--tabs-->
|
|
|
|
### ❌ Incorrect
|
|
|
|
```ts
|
|
/* eslint @typescript-eslint/no-non-null-asserted-nullish-coalescing: "error" */
|
|
|
|
foo! ?? bar;
|
|
foo.bazz! ?? bar;
|
|
foo!.bazz! ?? bar;
|
|
foo()! ?? bar;
|
|
|
|
let x!: string;
|
|
x! ?? '';
|
|
|
|
let x: string;
|
|
x = foo();
|
|
x! ?? '';
|
|
```
|
|
|
|
### ✅ Correct
|
|
|
|
```ts
|
|
/* eslint @typescript-eslint/no-non-null-asserted-nullish-coalescing: "error" */
|
|
|
|
foo ?? bar;
|
|
foo ?? bar!;
|
|
foo!.bazz ?? bar;
|
|
foo!.bazz ?? bar!;
|
|
foo() ?? bar;
|
|
|
|
// This is considered correct code because there's no way for the user to satisfy it.
|
|
let x: string;
|
|
x! ?? '';
|
|
```
|
|
|
|
## Options
|
|
|
|
```jsonc
|
|
// .eslintrc.json
|
|
{
|
|
"rules": {
|
|
"@typescript-eslint/no-non-null-asserted-nullish-coalescing": "warn"
|
|
}
|
|
}
|
|
```
|
|
|
|
This rule is not configurable.
|
|
|
|
## When Not To Use It
|
|
|
|
If you are not using TypeScript 3.7 (or greater), then you will not need to use this rule, as the nullish coalescing operator is not supported.
|
|
|
|
## Further Reading
|
|
|
|
- [TypeScript 3.7 Release Notes](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html)
|
|
- [Nullish Coalescing Proposal](https://github.com/tc39/proposal-nullish-coalescing)
|