Question

1. if (document.all)
2. document.body.style.behavior='url(#default#homepage)';
3. if (window.sidebar)

What’s those lines meaning in javascript? thank you.

Answer 1

Don’t use document.all:

if (document.all) {
   element = document.all[id];
else {
   element = document.getElementById(id);
}

1. document.all was introduced in Internet Explorer 4, because the W3C DOM hadn’t yet standardised a way of grabbing references to elements using their ID.
   By the time IE 5 came out, document.getElementById() had been standardised and as a result, IE 5 included support for it.
   More info here..

2. document.body.style.behavior='url(#default#homepage)' is used to set current page as home page in the IE.

3. if (window.sidebar) is a check for firefox