---
url: /docs/guide/usage/linter/rules/react/no-unsafe.md
---

### What it does

This rule identifies and restricts the use of unsafe React lifecycle methods.

### Why is this bad?

Certain lifecycle methods (`componentWillMount`, `componentWillReceiveProps`, and `componentWillUpdate`)
are considered unsafe and have been deprecated since React 16.9. They are frequently misused and cause
problems in async rendering. Using their `UNSAFE_` prefixed versions or the deprecated names themselves
should be avoided.

### Examples

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

```jsx
// By default, UNSAFE_ prefixed methods are flagged
class Foo extends React.Component {
  UNSAFE_componentWillMount() {}
  UNSAFE_componentWillReceiveProps() {}
  UNSAFE_componentWillUpdate() {}
}

// With checkAliases: true, non-prefixed versions are also flagged
class Bar extends React.Component {
  componentWillMount() {}
  componentWillReceiveProps() {}
  componentWillUpdate() {}
}
```

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

```jsx
class Foo extends React.Component {
  componentDidMount() {}
  componentDidUpdate() {}
  render() {}
}
```

## Configuration

This rule accepts a configuration object with the following properties:

### checkAliases

type: `boolean`

default: `false`

Whether to check for the non-prefixed lifecycle methods.
If `true`, this means `componentWillMount`, `componentWillReceiveProps`,
and `componentWillUpdate` will also be flagged, rather than just the
UNSAFE\_ versions. It is recommended to set this to `true` to fully
avoid unsafe lifecycle methods.

## How to use

## Version

This rule was added in v1.35.0.

## References