IMG's onload alternative usage _ image effects

The onload event of the picture, I believe that we are often used, especially in the control of the image output size.
But the onload also has some special usage. For example, recently I do Ajax, need to be in the onload when loading, generally use window onload event, but window onload event must be loaded after all the HTML elements to execute (including all the pictures, if the page has a picture missing on the trouble).
A lot of JS library classes, such as jquery and prototype have relative functions to simulate the implementation.
We can also use the OnLoad method of the picture to implement.
For example: it can be achieved.