@typescript-eslint/eslint-plugin/docs/rules/no-non-null-asserted-optional-chain.mdx

TypeScript plugin for ESLint

---
description: 'Disallow non-null assertions after an optional chain expression.'
---

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/no-non-null-asserted-optional-chain** for documentation.

`?.` optional chain expressions provide `undefined` if an object is `null` or `undefined`.
Using a `!` non-null assertion to assert the result of an `?.` optional chain expression is non-nullable is likely wrong.

> Most of the time, either the object was not nullable and did not need the `?.` for its property lookup, or the `!` is incorrect and introducing a type safety hole.

## Examples

<Tabs>
<TabItem value="❌ Incorrect">

```ts
foo?.bar!;
foo?.bar()!;
```

</TabItem>
<TabItem value="✅ Correct">

```ts
foo?.bar;
foo?.bar();
```

</TabItem>
</Tabs>

## When Not To Use It

If your project's types don't yet fully describe whether certain values may be nullable, such as if you're transitioning to `strictNullChecks`, this rule might create many false reports.
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

- [TypeScript 3.7 Release Notes](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html)
- [Optional Chaining Proposal](https://github.com/tc39/proposal-optional-chaining/)