---
url: /docs/guide/usage/linter/rules/typescript/no-confusing-non-null-assertion.md
---

### What it does

Disallow non-null assertion in locations that may be confusing.

### Why is this bad?

Using a non-null assertion (`!`) next to an assignment or equality check (`=` or `==` or
`===`) creates code that is confusing as it looks similar to an inequality check (`!=` or
`!==`). Using one next to an `in` or `instanceof` check is also confusing because it may
look like the operator is negated.

### Examples

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

```ts
a! == b; // a non-null assertions(`!`) and an equals test(`==`)
a !== b; // not equals test(`!==`)
a! === b; // a non-null assertions(`!`) and an triple equals test(`===`)
a! in b;
a! instanceof b;
```

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

```ts
a == b;
a !== b;
a === b;
```

## How to use

## Version

This rule was added in v0.6.1.

## References