Can someone explain the addLoadEvent by Simon Willison? I read over the explanation at http://simonwillison.net/2004/May/26/addLoadEvent/ but didn’t really get it.
A line by line explanation would be helpful.
What is the purpose of var oldonload = window.onload; Why do I need test typeof window.onload? Isn’t it always a function?
What is if(oldonload){ oldonload(); }?
function addLoadEvent(func){
var oldonload = window.onload;
if (typeof window.onload != 'function'){
window.onload = func;
} else {
window.onload = function(){
if(oldonload){
oldonload();
}
func();
}
}
}