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@typescript-eslint/eslint-plugin

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--- description: 'Enforce using `@ts-expect-error` over `@ts-ignore`.' --- import Tabs from '@theme/Tabs'; import TabItem from '@theme/TabItem'; > 🛑 This file is source code, not the primary documentation location! 🛑 > > See **https://typescript-eslint.io/rules/prefer-ts-expect-error** for documentation. :::danger Deprecated This rule has been deprecated in favor of [`@typescript-eslint/ban-ts-comment`](./ban-ts-comment.mdx). This rule (`@typescript-eslint/prefer-ts-expect-error`) will be removed in a future major version of typescript-eslint. When it was first created, `@typescript-eslint/ban-ts-comment` rule was only responsible for suggesting to remove `@ts-ignore` directive. It was later updated to suggest replacing `@ts-ignore` with `@ts-expect-error` directive, so that it replaces `@typescript-eslint/prefer-ts-expect-error` entirely. ::: TypeScript allows you to suppress all errors on a line by placing a comment starting with `@ts-ignore` or `@ts-expect-error` immediately before the erroring line. The two directives work the same, except `@ts-expect-error` causes a type error if placed before a line that's not erroring in the first place. This means it's easy for `@ts-ignore`s to be forgotten about, and remain in code even after the error they were suppressing is fixed. This is dangerous, as if a new error arises on that line it'll be suppressed by the forgotten about `@ts-ignore`, and so be missed. ## Examples This rule reports any usage of `@ts-ignore`, including a fixer to replace with `@ts-expect-error`. <Tabs> <TabItem value="❌ Incorrect"> ```ts // @ts-ignore const str: string = 1; /** * Explaining comment * * @ts-ignore */ const multiLine: number = 'value'; /** @ts-ignore */ const block: string = 1; const isOptionEnabled = (key: string): boolean => { // @ts-ignore: if key isn't in globalOptions it'll be undefined which is false return !!globalOptions[key]; }; ``` </TabItem> <TabItem value="✅ Correct"> ```ts // @ts-expect-error const str: string = 1; /** * Explaining comment * * @ts-expect-error */ const multiLine: number = 'value'; /** @ts-expect-error */ const block: string = 1; const isOptionEnabled = (key: string): boolean => { // @ts-expect-error: if key isn't in globalOptions it'll be undefined which is false return !!globalOptions[key]; }; ``` </TabItem> </Tabs> ## When Not To Use It If you are compiling against multiple versions of TypeScript and using `@ts-ignore` to ignore version-specific type errors, this rule might get in your way. You might consider using [ESLint disable comments](https://eslint.org/docs/latest/use/configure/rules#using-configuration-comments-1) for those specific situations instead of completely disabling this rule. ## Further Reading - [Original Implementing PR](https://github.com/microsoft/TypeScript/pull/36014)