How to Ensure the onload Event Fires Even with Cached Images?

Loading Images and Navigating Browser Cache with the onload Event

An image's onload event is essential for executing actions when an image has successfully loaded. However, the event can encounter limitations when dealing with cached images stored in the browser. This article explores how to overcome this issue and trigger the onload event consistently.

The Challenge: Cached Images and the onload Event

In web development, the onload event is attached to an element and triggered when the image is fully loaded. This allows developers to execute specific tasks after the image is visible to the user. However, cached images cached in the browser can bypass this event, resulting in no alert being displayed in cached image scenarios.

Solution 1: Setting onload Before Adding src

To ensure the onload event is triggered regardless of the caching status, modify the code sequence. Instead of setting the src attribute before the onload event, define the onload function first. This allows the browser to register the event handler before it attempts to load the image.

var img = new Image();
img.onload = function () {
   alert("image is loaded");
}
img.src = "img.jpg";

Solution 2: Using jQuery's load Event

An alternative approach involves utilizing jQuery, a widely adopted JavaScript library. jQuery's load event provides a solution when the standard onload event may not be triggered in cached image scenarios. The following code illustrates this technique:

var img = new Image();
// 'load' event
$(img).on('load', function() {
  alert("image is loaded");
});
img.src = "img.jpg";

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