Why not use Javascript handlers on the body element?

Question

As an answer to the question of \'How do you automatically set the focus to a textbox when a web page loads?\', Espo suggests using

Answer 1

There's nothing wrong with using the onload attribute in the element, provided:

• you have complete control of the page
• no other script that you use on the page currently or could have in the future will try and set an onload handler on the body element or the window object
• you know your own mind and are happy to have a small piece of script in your mark-up.

It's also worth noting that is a part of a formal standard (HTML 4) while window.onload is not, although it is implemented in all the major browsers going back many years.