How to Load Images Asynchronously with jQuery: A Step-by-Step Guide

Asynchronous Image Loading with jQuery

Coordinating the loading and display of images on your webpage can significantly impact its performance. Asynchronously loading images ensures minimal disruption to the user experience by granting control over the order and timing of image loading. jQuery, a versatile JavaScript library, offers convenient methods for handling asynchronous tasks, including image loading.

Asynchronous Image Loading Using XMLHttpRequest

One approach to loading images asynchronously is by utilizing theXMLHttpRequest (XHR) object. However, this method poses challenges, particularly when encountering errors or setting timeouts to catch 404 responses.

Alternative Method: Manipulating Image Elements

A more reliable method for asynchronously loading images involves creating an img element, setting its source attribute to the image URL, and observing its load event. This event-driven approach provides greater control over handling loading errors and checking image availability.

var img = $("<img />").attr('src', 'http://somedomain.com/image.jpg')
    .on('load', function() {
        if (!this.complete || typeof this.naturalWidth == "undefined" || this.naturalWidth == 0) {
            alert('Broken image!');
        } else {
            $("#something").append(img);
        }
    });

In this code snippet:

• A new img element is created and its source is set to the desired image URL.
• The on('load') event listener is attached to the img element, which will be invoked once the image is fully loaded.
• Within the event listener, the complete, naturalWidth, and naturalHeight properties are checked to validate if the image has loaded successfully. If any of these conditions are not met, an error message is displayed.
• If the image loads successfully, it is appended to a predetermined
  element with the ID "something".

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