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Using event.target in React to get the class name of an element

Get the class name of an element:

1. Set the attribute on the element onClickto the event handler function.
2. Access the element's class name as event.currentTarget.className.

export default function App() {
  const handleClick = event => {
    console.log('className 👉️', event.currentTarget.className);

    if (event.currentTarget.classList.contains('my-class')) {
      console.log('Element contains class');
    } else {
      console.log('Element does NOT contain class');
    }
  };

  return (
    <div>
      <div
        className="my-class second-class"
        onClick={handleClick}
      >
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      </div>
    </div>
  );
}

We set onClickthe attribute on the div element, so every time it is clicked, its handleClickfunction will be called.

const handleClick = event => {
  console.log('className 👉️', event.currentTarget.className);

  if (event.currentTarget.classList.contains('my-class')) {
    console.log('Element contains class');
  } else {
    console.log('Element does NOT contain class');
  }
};

We can event.currentTarget.classNameaccess handleClickthe class name of the element in the function through the property.

请注意, we used currentTargetthe property on the event because we want to access the element that the event listener is attached to.

The target property of the event gives us a reference to the element (possibly a descendant) that triggered the event.

If we need to access the class name of the element that was actually clicked, rather than the class name of the element the event listener is attached to, we can use the target property.

const handleClick = event => {
  console.log('className 👉️', event.target.className);
};

Using ref to get the class name of an element in React

This is a two-step process:

1. Set the ref attribute on the element.
2. Access the class name as ref.current.className.

import {useEffect, useRef} from 'react';

export default function App() {
  const ref = useRef(null);

  useEffect(() => {
    console.log('className 👉️', ref.current.className);

    if (ref.current.classList.contains('my-class')) {
      console.log('Element contains class');
    } else {
      console.log('Element does NOT contain class');
    }
  }, []);

  return (
    <div>
      <div className="my-class second-class" ref={ref}>
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      </div>
    </div>
  );
}

The code example uses ref to get the class name of an element when the component mounts.

useRef()The hook can be passed an initial value as a parameter.

const ref = useRef(null);

This hook returns a mutable ref object whose .currentattributes are initialized to the passed argument.

请注意, we have to access the current property of the ref object in order to access the div element on which we set the ref attribute.

useEffect(() => {
  console.log('className 👉️', ref.current.className);

  if (ref.current.classList.contains('my-class')) {
    console.log('Element contains class');
  } else {
    console.log('Element does NOT contain class');
  }
}, []);

When we pass a ref prop to an element, for example <div ref={myRef} />, React sets the ref object’s .current property to the corresponding DOM node.

We pass an empty dependencies array to useEffectthe hook, so it will only run when the component mounts.

The last step is to programmatically get the element's class name using the className property.