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Updating/Unmounting Lifecycle Methods


The first updating lifecycle method is called componentWillReceiveProps.

When a component instance updates, componentWillReceiveProps gets called before the rendering begins.

As one might expect, componentWillReceiveProps only gets called if the component will receive props:

// componentWillReceiveProps will get called here: ReactDOM.render( <Example prop="myVal" />, document.getElementById('app') ); // componentWillReceiveProps will NOT get called here: ReactDOM.render( <Example />, document.getElementById('app') );

Look in the code editor for an example of componentWillReceiveProps. Read it through and try to figure out how it works.

componentWillReceiveProps automatically gets passed one argument: an object called nextProps. nextProps is a preview of the upcoming props object that the component is about to receive.

On line 6, nextProps.text will evaluate to "Hello world".

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