Toggle a class on click in React

Toggle a class on click in React #

To toggle a class on click in React:

1. Set the onClick prop on the element.
2. Store the active state in a state variable.
3. Conditionally add the class using a ternary operator.

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

export default function App() {
  const [isActive, setIsActive] = useState(false);

  const handleClick = event => {
    // 👇️ toggle isActive state variable
    setIsActive(current => !current);
  };

  return (
    <div>
      <button className={isActive ? 'bg-salmon' : ''} onClick={handleClick}>
        Click
      </button>
    </div>
  );
}

And here is the css for the example.

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.bg-salmon {
  background-color: salmon;
  color: white;
}

We initialized the state for the isActive variable to false in the useState hook.

We set the onClick prop on the button element, so every time it is clicked, the handleClick function is invoked.

In our handleClick function, we simply toggle the isActive boolean.

We used a ternary operator to conditionally add the class to the element.

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<button className={isActive ? 'bg-salmon' : ''} onClick={handleClick}>
  Click
</button>

The ternary operator is very similar to an if/else statement.

In other words, if the isActive variable stores a true value, we add the bg-salmon class to the element, otherwise return an empty string.

Alternatively, you can use the classList.toggle() method to toggle a class on an element.

Copied!
import './App.css';

export default function App() {
  const handleClick = event => {

    // 👇️ toggle class on click
    event.currentTarget.classList.toggle('bg-salmon');
  };

  return (
    <div>
      <button onClick={handleClick}>Click</button>
    </div>
  );
}

We can access the element via the currentTarget property of the event object.

The currentTarget property on the event gives us access the element that the event listener is attached to.

Whereas the target property on the event gives us a reference to the element that triggered the event (could be a descendant).

The classList.toggle method removes an existing class from the element if the class is present. Otherwise, it adds the class to the element.