2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								---
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								id: 5a24c314108439a4d4036184
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								title: Render with an If-Else Condition
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								challengeType: 6
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								isRequired: false
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								---
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								## Description
  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< section  id = 'description' >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								Another application of using JavaScript to control your rendered view is to tie the elements that are rendered to a condition. When the condition is true, one view renders. When it's false, it's a different view. You can do this with a standard < code > if/else< / code >  statement in the < code > render()< / code >  method of a React component.
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< / section >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								## Instructions
  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< section  id = 'instructions' >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								MyComponent contains a < code > boolean< / code >  in its state which tracks whether you want to display some element in the UI or not. The < code > button< / code >  toggles the state of this value. Currently, it renders the same UI every time. Rewrite the < code > render()< / code >  method with an < code > if/else< / code >  statement so that if < code > display< / code >  is < code > true< / code > , you return the current markup. Otherwise, return the markup without the < code > h1< / code >  element.
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< strong > Note:< / strong >   You must write an < code > if/else< / code >  to pass the tests. Use of the ternary operator will not pass here. 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< / section >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								## Tests
  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< section  id = 'tests' >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```yml
							 
						 
					
						
							
								
									
										
										
										
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								tests:
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  -  text: < code > MyComponent</ code >  should exist and render.
							 
						 
					
						
							
								
									
										
										
										
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								    testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(MyComponent)); return mockedComponent.find('MyComponent').length === 1; })(), '< code > MyComponent< / code >  should exist and render.');
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  -  text: When < code > display</ code >  is set to < code > true</ code > , a < code > div</ code > , < code > button</ code > , and < code > h1</ code >  should render.
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(MyComponent)); const state_1 = () => { mockedComponent.setState({display: true}); return waitForIt(() => mockedComponent )}; const updated = await state_1(); assert(mockedComponent.find(''div'').length === 1 & &  mockedComponent.find(''div'').children().length === 2 & &  mockedComponent.find(''button'').length === 1 & &  mockedComponent.find(''h1'').length === 1, ''When < code > display< / code >  is set to < code > true< / code > , a < code > div< / code > , < code > button< / code > , and < code > h1< / code >  should render.''); }; '
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  -  text: When < code > display</ code >  is set to < code > false</ code > , only a < code > div</ code >  and < code > button</ code >  should render.
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(MyComponent)); const state_1 = () => { mockedComponent.setState({display: false}); return waitForIt(() => mockedComponent )}; const updated = await state_1(); assert(mockedComponent.find(''div'').length === 1 & &  mockedComponent.find(''div'').children().length === 1 & &  mockedComponent.find(''button'').length === 1 & &  mockedComponent.find(''h1'').length === 0, ''When < code > display< / code >  is set to < code > false< / code > , only a < code > div< / code >  and < code > button< / code >  should render.''); }; '
							 
						 
					
						
							
								
									
										
										
										
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								  -  text: The render method should use an < code > if/else</ code >  statement to check the condition of < code > this.state.display</ code > .
							 
						 
					
						
							
								
									
										
										
										
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								    testString: getUserInput => assert(getUserInput('index').includes('if') & &  getUserInput('index').includes('else'), 'The render method should use an < code > if/else< / code >  statement to check the condition of < code > this.state.display< / code > .');
							 
						 
					
						
							
								
									
										
										
										
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								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< / section >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								## Challenge Seed
  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< section  id = 'challengeSeed' >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< div  id = 'jsx-seed' >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```jsx
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								class MyComponent extends React.Component {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  constructor(props) {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    super(props);
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    this.state = {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								      display: true
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    this.toggleDisplay = this.toggleDisplay.bind(this);
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  toggleDisplay() {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    this.setState({
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								      display: !this.state.display
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    });
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  render() {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    // change code below this line
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    return (
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								       < div > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								         < button  onClick = {this.toggleDisplay} > Toggle Display< / button > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								         < h1 > Displayed!< / h1 > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								       < / div > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    );
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								};
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< / div >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								### After Test
  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< div  id = 'jsx-teardown' >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```js
							 
						 
					
						
							
								
									
										
										
										
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								ReactDOM.render(< MyComponent  / > , document.getElementById('root'))
							 
						 
					
						
							
								
									
										
										
										
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								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< / div >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< / section >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								## Solution
  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< section  id = 'solution' >  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```js
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								class MyComponent extends React.Component {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  constructor(props) {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    super(props);
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    this.state = {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								      display: true
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    }
							 
						 
					
						
							
								
									
										
										
										
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								 this.toggleDisplay = this.toggleDisplay.bind(this);
							 
						 
					
						
							
								
									
										
										
										
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								 }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  toggleDisplay() {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    this.setState({
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								      display: !this.state.display
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    });
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  render() {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    // change code below this line
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    if (this.state.display) {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								      return (
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								         < div > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								           < button  onClick = {this.toggleDisplay} > Toggle Display< / button > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								           < h1 > Displayed!< / h1 > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								         < / div > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								      );
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    } else {
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								      return (
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								        < div > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								           < button  onClick = {this.toggleDisplay} > Toggle Display< / button > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								         < / div > 
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								      );
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								    }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								  }
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								};
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								< / section >