@typescript-eslint/eslint-plugin
Version:
TypeScript plugin for ESLint
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text/mdx
---
description: 'Enforce using `-expect-error` over `-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 [`-eslint/ban-ts-comment`](./ban-ts-comment.mdx).
This rule (`-eslint/prefer-ts-expect-error`) will be removed in a future major version of typescript-eslint.
When it was first created, `-eslint/ban-ts-comment` rule was only responsible for suggesting to remove `-ignore` directive.
It was later updated to suggest replacing `-ignore` with `-expect-error` directive, so that it replaces `-eslint/prefer-ts-expect-error` entirely.
:::
TypeScript allows you to suppress all errors on a line by placing a comment starting with `-ignore` or `-expect-error` immediately before the erroring line.
The two directives work the same, except `-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 `-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 `-ignore`, and so be missed.
## Examples
This rule reports any usage of `-ignore`, including a fixer to replace with `-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 `-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)