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Conditionally set a CSS property to none in React display:

1. Stores a Boolean value in the state indicating whether the element should be displayed.
2. Conditionally styleset the display property in the element's <div> attribute.
3. For example, style={{display: isShown ? 'block' : 'none'}}.

import {useState} from 'react';

export default function App() {
  const [isShown, setIsShown] = useState(true);

  const handleClick = event => {
    // 👇️ toggle visibility
    setIsShown(current => !current);
  };

  return (
    <div>
      <button onClick={handleClick}>Toggle visibility</button>

      <div style={{display: isShown ? 'block' : 'none'}}>
        <h2>欢迎访问 迹忆客(jiyik.com)</h2>
      </div>
    </div>
  );
}

We use useStatethe hook to store a boolean value indicating whether an element should be shown.

Every time the button element is clicked, isShownthe boolean value is toggled, but this could be triggered by any other means.

请注意, we setIsShownpass a function to . This is important because setIsShownthe function we pass to is guaranteed to isShownbe called with the current (latest) value of the boolean.

If the new state is calculated using the previous state, a function can be passed to setState().

The displaystyle property of the div element's attribute is conditionally set using the ternary operator.

The ternary operator is if/elsevery similar to the statement.

If the value to the left of the question mark is true, the operator returns the value to the left of the colon, otherwise it returns the value to the right of the colon.

const result1 = 5 === 5 ? 'yes' : 'no';
console.log(result1); // 👉️ "yes"

const result2 = 5 === 10 ? 'yes' : 'no';
console.log(result2); // 👉️ "no"

If isShownthe state variable stores a real value, we set the display property to block . Otherwise, it is set to none .

The same approach can be used if we rely on setting class names for styles.

import {useState} from 'react';

// 👇️ import css file
import './App.css';

export default function App() {
  const [isShown, setIsShown] = useState(true);

  const handleClick = event => {
    setIsShown(current => !current);
  };

  // 👇️ using classes
  return (
    <div>
      <button onClick={handleClick}>Toggle visibility</button>

      <div className={isShown ? 'display-block' : 'display-none'}>
        <h2>欢迎访问 迹忆客(jiyik.com)</h2>
      </div>
    </div>
  );
}

Here is the css that defines display-blockthe and display-noneclasses.

.display-block {
  display: block;
}

.display-none {
  display: none;
}

The code snippet above achieves the same result using a class instead of a style attribute.

If the element you want to set the class on also has a different class, use template strings.

import {useState} from 'react';
import './App.css';

export default function App() {
  const [isShown, setIsShown] = useState(true);

  const handleClick = event => {
    // 👇️ toggle visibility
    setIsShown(current => !current);
  };

  return (
    <div>
      <button onClick={handleClick}>Toggle visibility</button>

      <div className={`my-class ${isShown ? 'display-block' : 'display-none'}`}>
        <h2>欢迎访问 迹忆客(jiyik.com)</h2>
      </div>
    </div>
  );
}

${}The syntax enables us to evaluate expressions directly in template strings.