How Can I Use Callbacks to Handle Image Loading in JavaScript?

Loading Images in JavaScript with Callbacks

When working with images, it's often necessary to know when they've finished loading. This allows you to perform actions based on the state of the image, such as displaying it or processing it further.

Callback Method

In JavaScript, one common approach to handling image loading is to use a callback function. A callback is a function that is invoked when a specific event occurs, such as the image being fully loaded.

The .complete property of an image element indicates its loading status. If the image is already loaded, you can directly invoke the callback function. Otherwise, you can attach an 'onload' event listener to the image.

Here's an example:

var img = document.querySelector('img');

function loaded() {
  alert('loaded');
}

if (img.complete) {
  loaded();
} else {
  img.addEventListener('load', loaded);
  img.addEventListener('error', function() {
    alert('error');
  });
}

Source: http://www.html5rocks.com/en/tutorials/es6/promises/

By leveraging this approach, you can reliably determine image loading status and execute appropriate actions through the provided callback function.

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