The onloadstart property of the GlobalEventHandlers mixin is an EventHandler representing the code to be called when the loadstart event is raised (when progress has begun on the loading of a resource.)


img.onloadstart = funcRef;


funcRef is the handler function to be called when the resource's loadstart event fires.


HTML content

<img src="myImage.jpg">

JavaScript content

// 'loadstart' fires first, then 'load', then 'loadend'
image.addEventListener('load', function(e) {
  console.log('Image loaded');
image.addEventListener('loadstart', function(e) {
  console.log('Image load started');
image.addEventListener('loadend', function(e) {
  console.log('Image load finished');


Specification Status Comment
WHATWG HTML Living Standard
The definition of 'onloadstart' in that specification.
Living Standard Initial definition

Browser Compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support (Yes) 20 (12.10240) (Yes)
52 (52)[1]
(Yes) (Yes) ?
Feature Android Android Webview Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support (Yes) (Yes) 20 (12.10240) (Yes)
52.0 (52)[1]
(Yes) (Yes) ? (Yes)

[1] As of Firefox 52, The loadstart event is now fired on <img> elements.

Document Tags and Contributors

 Contributors to this page: Sebastianz, chrisdavidmills
 Last updated by: Sebastianz,