frontend - What is this JavaScript hack? -

i found code in javascript, , wondering if kind of hack, or mistake :

var img = new image(); img.src = myhttpsrc; img.onload = function () {     img.onload = null; }; 

the code seems load image myhttpsrc. there event handler onload triggered when loaded. handler removing once load completed.

this not hack, onload handler not doing other removing seems redundant.