freeCodeCamp/curriculum/challenges/russian/03-front-end-libraries/react/use-a-ternary-expression-for-conditional-rendering.russian.md

---
id: 5a24c314108439a4d4036187
title: Use a Ternary Expression for Conditional Rendering
challengeType: 6
isRequired: false
forumTopicId: 301414
localeTitle: Использование терминологического выражения для условного рендеринга
---

## Description
<section id='description'>
Прежде чем перейти к динамическим методам рендеринга, есть последний способ использовать встроенные условия JavaScript для рендеринга того, что вы хотите: <em><strong>трехмерный оператор</strong></em> . Тернарный оператор часто используется как ярлык для операторов <code>if/else</code> в JavaScript. Они не настолько устойчивы, как традиционные инструкции <code>if/else</code> , но они очень популярны среди разработчиков React. Одна из причин этого заключается в том, что JSX скомпилирован, <code>if/else</code> инструкции не могут быть вставлены непосредственно в код JSX. Возможно, вы заметили это несколько проблем назад - когда требовался оператор <code>if/else</code> , он всегда находился <em>за пределами</em> оператора <code>return</code> . Тернарные выражения могут быть отличной альтернативой, если вы хотите реализовать условную логику в своем JSX. Напомним, что тройной оператор состоит из трех частей, но вы можете комбинировать несколько тройных выражений. Вот основной синтаксис: <blockquote> состояние ? выражениеIfTrue: выражениеIfFalse </blockquote>
</section>

## Instructions
<section id='instructions'>
The code editor has three constants defined within the <code>CheckUserAge</code> component's <code>render()</code> method. They are called <code>buttonOne</code>, <code>buttonTwo</code>, and <code>buttonThree</code>. Each of these is assigned a simple JSX expression representing a button element. First, initialize the state of <code>CheckUserAge</code> with <code>input</code> and <code>userAge</code> both set to values of an empty string.
Once the component is rendering information to the page, users should have a way to interact with it. Within the component's <code>return</code> statement, set up a ternary expression that implements the following logic: when the page first loads, render the submit button, <code>buttonOne</code>, to the page. Then, when a user enters their age and clicks the button, render a different button based on the age. If a user enters a number less than <code>18</code>, render <code>buttonThree</code>. If a user enters a number greater than or equal to <code>18</code>, render <code>buttonTwo</code>.
</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: The <code>CheckUserAge</code> component should render with a single <code>input</code> element and a single <code>button</code> element.
    testString: assert(Enzyme.mount(React.createElement(CheckUserAge)).find('div').find('input').length === 1 && Enzyme.mount(React.createElement(CheckUserAge)).find('div').find('button').length === 1);
  - text: The <code>CheckUserAge</code> component&apos;s state should be initialized with a property of <code>userAge</code> and a property of <code>input</code>, both set to a value of an empty string.
    testString: assert(Enzyme.mount(React.createElement(CheckUserAge)).state().input === '' && Enzyme.mount(React.createElement(CheckUserAge)).state().userAge === '');
  - text: When the <code>CheckUserAge</code> component is first rendered to the DOM, the <code>button</code>&apos;s inner text should be Submit.
    testString: assert(Enzyme.mount(React.createElement(CheckUserAge)).find('button').text() === 'Submit');
  - text: When a number of less than 18 is entered into the <code>input</code> element and the <code>button</code> is clicked, the <code>button</code>&apos;s inner text should read <code>You Shall Not Pass</code>.
    testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(CheckUserAge)); const initialButton = mockedComponent.find(''button'').text(); const enter3AndClickButton = () => { mockedComponent.find(''input'').simulate(''change'', {target: { value: ''3'' }}); mockedComponent.find(''button'').simulate(''click''); return waitForIt(() => { mockedComponent.update(); return mockedComponent.find(''button'').text(); }); }; const enter17AndClickButton = () => { mockedComponent.find(''input'').simulate(''change'', {target: { value: ''17'' }}); mockedComponent.find(''button'').simulate(''click''); return waitForIt(() => { mockedComponent.update(); return mockedComponent.find(''button'').text(); }); }; const userAge3 = await enter3AndClickButton(); const userAge17 = await enter17AndClickButton(); assert(initialButton === ''Submit'' && userAge3 === ''You Shall Not Pass'' && userAge17 === ''You Shall Not Pass''); }; '
  - text: When a number greater than or equal to 18 is entered into the <code>input</code> element and the <code>button</code> is clicked, the <code>button</code>&apos;s inner text should read <code>You May Enter</code>.
    testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(CheckUserAge)); const initialButton = mockedComponent.find(''button'').text(); const enter18AndClickButton = () => { mockedComponent.find(''input'').simulate(''change'', {target: { value: ''18'' }}); mockedComponent.find(''button'').simulate(''click''); return waitForIt(() => { mockedComponent.update(); return mockedComponent.find(''button'').text(); }); }; const enter35AndClickButton = () => { mockedComponent.find(''input'').simulate(''change'', {target: { value: ''35'' }}); mockedComponent.find(''button'').simulate(''click''); return waitForIt(() => { mockedComponent.update(); return mockedComponent.find(''button'').text(); }); }; const userAge18 = await enter18AndClickButton(); const userAge35 = await enter35AndClickButton(); assert(initialButton === ''Submit'' && userAge18 === ''You May Enter'' && userAge35 === ''You May Enter''); }; '
  - text: Once a number has been submitted, and the value of the <code>input</code> is once again changed, the <code>button</code> should return to reading <code>Submit</code>.
    testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(CheckUserAge)); const enter18AndClickButton = () => { mockedComponent.find(''input'').simulate(''change'', {target: { value: ''18'' }}); mockedComponent.find(''button'').simulate(''click''); return waitForIt(() => { mockedComponent.update(); return mockedComponent.find(''button'').text(); }); }; const changeInputDontClickButton = () => { mockedComponent.find(''input'').simulate(''change'', {target: { value: ''5'' }}); return waitForIt(() => { mockedComponent.update(); return mockedComponent.find(''button'').text(); }); }; const enter10AndClickButton = () => { mockedComponent.find(''input'').simulate(''change'', {target: { value: ''10'' }}); mockedComponent.find(''button'').simulate(''click''); return waitForIt(() => { mockedComponent.update(); return mockedComponent.find(''button'').text(); }); }; const userAge18 = await enter18AndClickButton(); const changeInput1 = await changeInputDontClickButton(); const userAge10 = await enter10AndClickButton(); const changeInput2 = await changeInputDontClickButton(); assert(userAge18 === ''You May Enter'' && changeInput1 === ''Submit'' && userAge10 === ''You Shall Not Pass'' && changeInput2 === ''Submit''); }; '
  - text: Your code should not contain any <code>if/else</code> statements.
    testString: assert(new RegExp(/(\s|;)if(\s|\()/).test(Enzyme.mount(React.createElement(CheckUserAge)).instance().render.toString()) === false);

```

</section>

## Challenge Seed
<section id='challengeSeed'>

<div id='jsx-seed'>

```jsx
const inputStyle = {
  width: 235,
  margin: 5
}

class CheckUserAge extends React.Component {
  constructor(props) {
    super(props);
    // change code below this line

    // change code above this line
    this.submit = this.submit.bind(this);
    this.handleChange = this.handleChange.bind(this);
  }
  handleChange(e) {
    this.setState({
      input: e.target.value,
      userAge: ''
    });
  }
  submit() {
    this.setState({
      userAge: this.state.input
    });
  }
  render() {
    const buttonOne = <button onClick={this.submit}>Submit</button>;
    const buttonTwo = <button>You May Enter</button>;
    const buttonThree = <button>You Shall Not Pass</button>;
    return (
      <div>
        <h3>Enter Your Age to Continue</h3>
        <input
          style={inputStyle}
          type="number"
          value={this.state.input}
          onChange={this.handleChange} /><br />
        {
          /* change code here */
        }
      </div>
    );
  }
};

```

</div>

### After Tests
<div id='jsx-teardown'>

```jsx
ReactDOM.render(<CheckUserAge />, document.getElementById('root'))

```

</div>

</section>

## Solution
<section id='solution'>

```jsx
const inputStyle = {
  width: 235,
  margin: 5
}

class CheckUserAge extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      userAge: '',
      input: ''
    }
    this.submit = this.submit.bind(this);
    this.handleChange = this.handleChange.bind(this);
  }
  handleChange(e) {
    this.setState({
      input: e.target.value,
      userAge: ''
    });
  }
  submit() {
    this.setState({
      userAge: this.state.input
    });
  }
  render() {
    const buttonOne = <button onClick={this.submit}>Submit</button>;
    const buttonTwo = <button>You May Enter</button>;
    const buttonThree = <button>You Shall Not Pass</button>;
    return (
      <div>
        <h3>Enter Your Age to Continue</h3>
        <input
          style={inputStyle}
          type="number"
          value={this.state.input}
          onChange={this.handleChange} /><br />
          {
            this.state.userAge === '' ?
            buttonOne :
            this.state.userAge >= 18 ?
            buttonTwo :
            buttonThree
          }
      </div>
    );
  }
};
```

</section>