Is it necessary to set onload function before setting src for an image object?

Question

I was told it is necessary to set the onload function before setting src for an image object. I\'ve searched in SO for this.

I found this c

Answer 1

As soon as you assign the src a value, the image will load. If it loads before the onload is reached, your onload will not fire.

To support ALL implementations, I strongly suggest to assign the onload handler before setting the src.

It is my experience (21+ years of JS) that you MUST set onload first - especially in IE which did not even support the image object when I started with JS.

If you get issues about the cached image not firing, add +"?"+new Date().getTime() when you set the src next time to avoid cache.

Here is the example from MDN which also uses the order I have suggested

Creating an image from scratch

Another SO link image.onload not firing twice in IE7