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Calling multiple onClick functions in React:

1. Sets the onClick attribute on the element.
2. Call other functions in the event handling function.
3. An event handling function can call as many other functions as needed.

export default function App() {
  const sum = (a, b) => {
    return a + b;
  };

  const multiply = (a, b) => {
    return a * b;
  };

  return (
    <div>
      <button
        onClick={event => {
          console.log('function 1:', sum(5, 5));
          console.log('function 2:', multiply(5, 5));
        }}
      >
        Click
      </button>
    </div>
  );
}

We set onClickthe property on the button, so each time it is clicked, the provided event handler function will be called.

<button
  onClick={event => {
    console.log('function 1:', sum(5, 5));
    console.log('function 2:', multiply(5, 5));
  }}
>
  Click
</button>

The event handler takes the event object as a parameter and calls the sum()and multiply()functions.

We can use this method to call as many functions as needed in a single event handler.

Extract event handlers outside of JSX code

Another more readable approach is to extract the event handlers outside of the JSX code.

export default function App() {
  const sum = (a, b) => {
    return a + b;
  };

  const multiply = (a, b) => {
    return a * b;
  };

  const handleClick = event => {
    console.log(event.target);

    console.log('function 1:', sum(5, 5));
    console.log('function 2:', multiply(5, 5));
  };

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

Each time the button is clicked, handleClickthe function is called and the event object is passed to it.

const handleClick = event => {
  console.log(event.target);

  console.log('function 1:', sum(5, 5));
  console.log('function 2:', multiply(5, 5));
};

We can handleClickcall as many other functions from within a function as we want.

If any function expects an event object as an argument, make sure to forward it in the call.

请注意, we are passing a function to the onClick property, rather than the result of calling a function.

<button onClick={handleClick}>Click</button>

If you pass the result of calling handleClicka function to onClickthe property, for example onClick={handleClick()}, the function will be called immediately when the page loads, which is not what we want.