---
id: pure-render-mixin
title: PureRenderMixin
layout: docs
category: Reference
permalink: docs/pure-render-mixin-old.html
---

> Note

> The `PureRenderMixin` mixin predates `React.PureComponent`. This reference doc is provided for legacy purposes, and you should consider using [`React.PureComponent`](/docs/react-api.html#reactpurecomponent) instead.

If your React component's render function renders the same result given the same props and state, you can use this mixin for a performance boost in some cases.

Example:

```js
var PureRenderMixin = require('react-addons-pure-render-mixin');
var createReactClass = require('create-react-class');
createReactClass({
  mixins: [PureRenderMixin],

  render: function() {
    return <div className={this.props.className}>foo</div>;
  }
});
```

Example using ES6 class syntax:

```js
import PureRenderMixin from 'react-addons-pure-render-mixin';
class FooComponent extends React.Component {
  constructor(props) {
    super(props);
    this.shouldComponentUpdate = PureRenderMixin.shouldComponentUpdate.bind(this);
  }

  render() {
    return <div className={this.props.className}>foo</div>;
  }
}
```

Under the hood, the mixin implements [shouldComponentUpdate](/docs/component-specs.html#updating-shouldcomponentupdate), in which it compares the current props and state with the next ones and returns `false` if the equalities pass.

> Note:
>
> This only shallowly compares the objects. If these contain complex data structures, it may produce false-negatives for deeper differences. Only mix into components which have simple props and state, or use `forceUpdate()` when you know deep data structures have changed. Or, consider using [immutable objects](https://immutable-js.com/) to facilitate fast comparisons of nested data.
>
> Furthermore, `shouldComponentUpdate` skips updates for the whole component subtree. Make sure all the children components are also "pure".