state
in React applications in more complex ways than what you've seen so far. One example is to monitor the status of a value, then render the UI conditionally based on this value. There are several different ways to accomplish this, and the code editor shows one method.
MyComponent
has a visibility
property which is initialized to false
. The render method returns one view if the value of visibility
is true, and a different view if it is false.
Currently, there is no way of updating the visibility
property in the component's state
. The value should toggle back and forth between true and false. There is a click handler on the button which triggers a class method called toggleVisibility()
. Define this method so the state
of visibility
toggles to the opposite value when the method is called. If visibility
is false
, the method sets it to true
, and vice versa.
Finally, click the button to see the conditional rendering of the component based on its state
.
Hint: Don't forget to bind the this
keyword to the method in the constructor!
MyComponent
should return a div
element which contains a button
.
testString: 'assert.strictEqual(Enzyme.mount(React.createElement(MyComponent)).find("div").find("button").length, 1, "MyComponent
should return a div
element which contains a button
.");'
- text: The state of MyComponent
should initialize with a visibility
property set to false
.
testString: 'assert.strictEqual(Enzyme.mount(React.createElement(MyComponent)).state("visibility"), false, "The state of MyComponent
should initialize with a visibility
property set to false
.");'
- text: Clicking the button element should toggle the visibility
property in state between true
and false
.
testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(MyComponent)); const first = () => { mockedComponent.setState({ visibility: false }); return waitForIt(() => mockedComponent.state("visibility")); }; const second = () => { mockedComponent.find("button").simulate("click"); return waitForIt(() => mockedComponent.state("visibility")); }; const third = () => { mockedComponent.find("button").simulate("click"); return waitForIt(() => mockedComponent.state("visibility")); }; const firstValue = await first(); const secondValue = await second(); const thirdValue = await third(); assert(!firstValue && secondValue && !thirdValue, "Clicking the button element should toggle the visibility
property in state between true
and false
."); }; '
```