react.dev/content/docs/reference-pure-render-mixin.md

id	title	layout	category	permalink
pure-render-mixin	PureRenderMixin	docs	Reference	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 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:

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:

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, 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 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".