docs/rules/no-did-update-set-state.md
# Disallow usage of setState in componentDidUpdate (`react/no-did-update-set-state`)
<!-- end auto-generated rule header -->
Updating the state after a component update will trigger a second `render()` call and can lead to property/layout thrashing.
## Rule Details
Examples of **incorrect** code for this rule:
```jsx
var Hello = createReactClass({
componentDidUpdate: function() {
this.setState({
name: this.props.name.toUpperCase()
});
},
render: function() {
return <div>Hello {this.state.name}</div>;
}
});
```
Examples of **correct** code for this rule:
```jsx
var Hello = createReactClass({
componentDidUpdate: function() {
this.props.onUpdate();
},
render: function() {
return <div>Hello {this.props.name}</div>;
}
});
```
```jsx
var Hello = createReactClass({
componentDidUpdate: function() {
this.onUpdate(function callback(newName) {
this.setState({
name: newName
});
});
},
render: function() {
return <div>Hello {this.props.name}</div>;
}
});
```
## Rule Options
```js
...
"react/no-did-update-set-state": [<enabled>, <mode>]
...
```
### `disallow-in-func` mode
By default this rule forbids any call to `this.setState` in `componentDidUpdate` outside of functions. The `disallow-in-func` mode makes this rule more strict by disallowing calls to `this.setState` even within functions.
Examples of **incorrect** code for this rule:
```jsx
var Hello = createReactClass({
componentDidUpdate: function() {
this.setState({
name: this.props.name.toUpperCase()
});
},
render: function() {
return <div>Hello {this.state.name}</div>;
}
});
```
```jsx
var Hello = createReactClass({
componentDidUpdate: function() {
this.onUpdate(function callback(newName) {
this.setState({
name: newName
});
});
},
render: function() {
return <div>Hello {this.state.name}</div>;
}
});
```