componentWillReceiveProps()
which is called whenever a component is receiving new props. This method receives the new props as an argument, which is usually written as nextProps
. You can use this argument and compare with this.props
and perform actions before the component updates. For example, you may call setState()
locally before the update is processed.
Another method is componentDidUpdate()
, and is called immediately after a component re-renders. Note that rendering and mounting are considered different things in the component lifecycle. When a page first loads, all components are mounted and this is where methods like componentWillMount()
and componentDidMount()
are called. After this, as state changes, components re-render themselves. The next challenge covers this in more detail.
Dialog
receives message
props from its parent, the Controller
component. Write the componentWillReceiveProps()
method in the Dialog
component and have it log this.props
and nextProps
to the console. You'll need to pass nextProps
as an argument to this method and although it's possible to name it anything, name it nextProps
here.
Next, add componentDidUpdate()
in the Dialog
component, and log a statement that says the component has updated. This method works similar to componentWillUpdate()
, which is provided for you. Now click the button to change the message and watch your browser console. The order of the console statements show the order the methods are called.
Note: You'll need to write the lifecycle methods as normal functions and not as arrow functions to pass the tests (there is also no advantage to writing lifecycle methods as arrow functions).
Controller
component should render the Dialog
component as a child.
testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(Controller)); return mockedComponent.find('Controller').length === 1 && mockedComponent.find('Dialog').length === 1; })(), 'The Controller
component should render the Dialog
component as a child.');
- text: The componentWillReceiveProps
method in the Dialog
component should log this.props
to the console.
testString: assert((function() { const lifecycleChild = React.createElement(Dialog).type.prototype.componentWillReceiveProps.toString().replace(/ /g,''); return lifecycleChild.includes('console.log') && lifecycleChild.includes('this.props') })(), 'The componentWillReceiveProps
method in the Dialog
component should log this.props
to the console.');
- text: The componentWillReceiveProps
method in the Dialog
component should log nextProps
to the console.
testString: assert((function() { const lifecycleChild = React.createElement(Dialog).type.prototype.componentWillReceiveProps.toString().replace(/ /g,''); const nextPropsAsParameterTest = /componentWillReceiveProps(| *?= *?)(\(|)nextProps(\)|)( *?=> *?{| *?{|{)/; const nextPropsInConsoleLogTest = /console\.log\(.*?nextProps\b.*?\)/; return ( lifecycleChild.includes('console.log') && nextPropsInConsoleLogTest.test(lifecycleChild) && nextPropsAsParameterTest.test(lifecycleChild) ); })(), 'The componentWillReceiveProps
method in the Dialog
component should log nextProps
to the console.');
- text: The Dialog
component should call the componentDidUpdate
method and log a message to the console.
testString: assert((function() { const lifecycleChild = React.createElement(Dialog).type.prototype.componentDidUpdate.toString().replace(/ /g,''); return lifecycleChild.length !== 'undefined' && lifecycleChild.includes('console.log'); })(), 'The Dialog
component should call the componentDidUpdate
method and log a message to the console.');
```