---
url: /docs/guide/usage/linter/rules/eslint/no-unused-expressions.md
---

### What it does

This rule disallows unused expressions.

### Why is this bad?

Unused expressions are usually a mistake. They can be a symptom of a bug or a misunderstanding of the code.

### Examples

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

```ts
Set<number>;
1 as number;
window!;
```

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

```ts
const foo = new Set<number>();
```

## Configuration

This rule accepts a configuration object with the following properties:

### allowShortCircuit

type: `boolean`

default: `false`

When set to `true`, allows short circuit evaluations in expressions.

### allowTaggedTemplates

type: `boolean`

default: `false`

When set to `true`, allows tagged template literals in expressions.

### allowTernary

type: `boolean`

default: `false`

When set to `true`, allows ternary operators in expressions.

### enforceForJSX

type: `boolean`

default: `false`

When set to `true`, enforces the rule for unused JSX expressions also.

### ignoreDirectives

type: `boolean`

default: `false`

When set to `true`, allows directive prologues.

## How to use

## Version

This rule was added in v0.14.0.

## References