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How to Interact with Events in a React Application

How to Interact with Events in a React Application

In a React application, managing events is made easy with React’s built-in event handling system. Say goodbye to using addEventListener! In this article, we will explore how to interact with events in React.

Event Handling in React

Event handling in React is similar to handling events in plain old JavaScript, with a few key differences. Let’s consider the following example from a previous article about managing state in React:

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const CurrencySwitcher = props => {
  return (
    <button onClick={props.handleChangeCurrency}>
      Current currency is {props.currency}. Change it!
    </button>
  );
};

As you can see, the event handler handleChangeCurrency is passed as a prop to the onClick event. This is similar to using JavaScript event handlers in HTML, except that everything is defined in JavaScript rather than in HTML, and you’re passing a function instead of a string.

Although the event names are similar to JavaScript event names, there is a slight difference in naming conventions. In React, event names use camelCase, so onclick becomes onClick and onsubmit becomes onSubmit.

For reference, here’s an example of old school HTML with JavaScript events mixed in:

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<button onclick="handleChangeCurrency()">...</button>

Event Handlers as Methods

In React, it’s a convention to have event handlers defined as methods on the Component class. Here’s an example:

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class Converter extends React.Component {
  handleChangeCurrency = event => {
    this.setState({ currency: this.state.currency === '€' ? '$' : '€' });
  }
}

All event handlers in React receive an event object that adheres to the W3C UI Events specification, ensuring cross-browser compatibility.

Binding this in Methods

When defining methods in React components, it’s important to remember to bind this. By default, methods in ES6 classes are not bound, meaning that this is not defined unless you define methods as arrow functions. Here’s an example:

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class Converter extends React.Component {
  handleClick = e => {
    /* ... */
  }
  // ...
}

In order to ensure this is properly bound when using the property initializer syntax with Babel (which is enabled by default in create-react-app), you don’t need to manually bind this. However, if you’re not using this syntax, you must manually bind this in the constructor, like so:

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class Converter extends React.Component {
  constructor(props) {
    super(props);
    this.handleClick = this.handleClick.bind(this);
  }
  handleClick(e) {
    /* ... */
  }
}

Events Supported in React

React supports a wide range of events that you can use in your applications. Here’s a summary list of the events supported:

  • Clipboard: onCopy, onCut, onPaste
  • Composition: onCompositionEnd, onCompositionStart, onCompositionUpdate
  • Keyboard: onKeyDown, onKeyPress, onKeyUp
  • Focus: onFocus, onBlur
  • Form: onChange, onInput, onSubmit
  • Mouse: onClick, onContextMenu, onDoubleClick, onDrag, onDragEnd, onDragEnter, onDragExit, onDragLeave, onDragOver, onDragStart, onDrop, onMouseDown, onMouseEnter, onMouseLeave, onMouseMove, onMouseOut, onMouseOver, onMouseUp
  • Selection: onSelect
  • Touch: onTouchCancel, onTouchEnd, onTouchMove, onTouchStart
  • UI: onScroll
  • Mouse Wheel: onWheel
  • Media: onAbort, onCanPlay, onCanPlayThrough, onDurationChange, onEmptied, onEncrypted, onEnded, onError, onLoadedData, onLoadedMetadata, onLoadStart, onPause, onPlay, onPlaying, onProgress, onRateChange, onSeeked, onSeeking, onStalled, onSuspend, onTimeUpdate, onVolumeChange, onWaiting
  • Image: onLoad, onError
  • Animation: onAnimationStart, onAnimationEnd, onAnimationIteration
  • Transition: onTransitionEnd

With the flexibility and power of React’s event handling system, you can easily build interactive and dynamic applications.

tags: [“React”, “event handling”, “React events”, “event handlers”, “event names”, “binding this”, “supported events”]