How to Ensure an Image\'s `onload` Event Fires Even With Browser Caching?

Cached Image Loading and Browser Cache

When attempting to display an alert after loading an image, the .onload event may fail to trigger if the image has been cached in the browser. To ensure the alert is displayed regardless of caching, there are several approaches:

Setting onload Property Before Source

Configure the .onload property before setting the source (src) of the image. This ensures that the onload event listener is registered before the browser checks its cache for the image:

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

Utilizing jQuery Event Handler

Alternatively, utilize jQuery's .on('load') event handler. This method is particularly effective for dynamically generated images:

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

Both methods effectively trigger the alert event regardless of whether the image is cached or not. By modifying the order of event registration or utilizing jQuery, the .onload event can be guaranteed to fire even if the image resides in the browser cache.

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