How to Bind Arrow Keys in JavaScript and jQuery?

Binding Arrow Keys in JavaScript

In some applications, it becomes necessary to bind certain functions to specific keys on the keyboard, such as the arrow keys. In this article, we'll explore how to bind arrow keys in JavaScript and jQuery, focusing on the left and right arrows.

Using Standard JavaScript

The simplest method to handle key events in vanilla JavaScript is through the document.onkeydown event listener. By attaching a function to this event, we can check for the key code of the pressed key, which corresponds to the physical key on the keyboard. Here's an example:

<code class="js">document.onkeydown = function(e) {
  switch (e.which) {
    case 37: // Left arrow
      // Do something
      break;

    case 39: // Right arrow
      // Do something else
      break;
  }
  e.preventDefault(); // Prevent default behavior (like scrolling)
};</code>

Using jQuery

jQuery provides a more concise and convenient way to bind event listeners. Similar to the previous approach, we can use the keydown event to detect arrow key presses:

<code class="js">$(document).on("keydown", function(e) {
  switch (e.which) {
    case 37: // Left arrow
      // Do something
      break;

    case 39: // Right arrow
      // Do something else
      break;
  }
  e.preventDefault(); // Prevent default behavior (like scrolling)
});</code>

IE8 Compatibility

For browsers like IE8 that don't support the which property on event objects, we can use the following code:

<code class="js">e = e || window.event;
switch (e.which || e.keyCode) {
  case 37: // Left arrow
    // Do something
    break;

  case 39: // Right arrow
    // Do something else
    break;
}</code>

Note on Key Codes

The key codes used here (37 and 39) correspond to the left and right arrow keys, respectively. You can find key codes for other keys on the official JavaScript or jQuery documentation websites.

Modern JavaScript

In more recent versions of JavaScript, the which property has been deprecated in favor of KeyboardEvent.key. Here's an updated example using KeyboardEvent.key:

<code class="js">document.onkeydown = function(e) {
  switch (e.key) {
    case "ArrowLeft": // Left arrow
      // Do something
      break;

    case "ArrowRight": // Right arrow
      // Do something else
      break;
  }
  e.preventDefault(); // Prevent default behavior (like scrolling)
};</code>

By implementing these methods, you can easily bind specific functions to the left and right arrow keys, allowing for efficient keyboard interaction in your applications.

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