# react/no-is-mounted

> Disallow `this.isMounted()`

`isMounted()` only exists on components made with `createReactClass`. In a class that extends `React.Component`, `this.isMounted` is `undefined` and the call throws.

It's mostly used to skip a `setState` after the component is gone. That hides the real problem: a request, timer or subscription that's still running and still holds on to the component. Cancel it in `componentWillUnmount`.

{/* Generated by src/codegen/lint-rule-docs.ts. Do not edit this section. */}

## Configure

Off by default. To turn it on:

```toml bunfig.toml
[lint.rules]
"react/no-is-mounted" = "error" # or "warn"
```

{/* End of the generated section. */}

## Examples

Reported:

{/* bad */}
```jsx
class Profile extends React.Component {
  componentDidMount() {
    loadUser(this.props.id).then(user => {
      if (this.isMounted()) {
        this.setState({ user });
      }
    });
  }
}
```

Not reported:

{/* good */}
```jsx
class Profile extends React.Component {
  controller = new AbortController();

  componentDidMount() {
    loadUser(this.props.id, { signal: this.controller.signal }).then(user => {
      this.setState({ user });
    });
  }

  componentWillUnmount() {
    this.controller.abort();
  }
}
```