-- Main.shssdhakchina - 01 Feb 2022

React Events

Just like HTML DOM events, React can perform actions based on user events.

React has the same events as HTML: click, change, mouseover etc.

Adding Events

React events are written in camelCase syntax:

onClick instead of onclick.

React event handlers are written inside curly braces:

onClick={shoot} instead of onClick="shoot()".

React:

<button onClick={shoot}>Take the Shot!</button>

HTML:

<button onclick="shoot()">Take the Shot!</button>

Example: Put the shoot function inside the Football component:

function Football() {
  const shoot = () => {
    alert("Great Shot!");
  }

  return (
    <button onClick={shoot}>Take the shot!</button>
  );
}

ReactDOM.render(<Football />, document.getElementById('root'));

Passing Arguments

To pass an argument to an event handler, use an arrow function.

Example: Send "Goal!" as a parameter to the shoot function, using arrow function:

function Football() {
  const shoot = (a) => {
    alert(a);
  }

  return (
    <button onClick={() => shoot("Goal!")}>Take the shot!</button>
  );
}

ReactDOM.render(<Football />, document.getElementById('root'));

React Event Object

Event handlers have access to the React event that triggered the function.

In our example the event is the "click" event.

Example: Arrow Function: Sending the event object manually:

function Football() {
  const shoot = (a, b) => {
    alert(b.type);
    /*
    'b' represents the React event that triggered the function,
    in this case the 'click' event
    */
  }

  return (
    <button onClick={(event) => shoot("Goal!", event)}>Take the shot!</button>
  );
}

ReactDOM.render(<Football />, document.getElementById('root'));