What reason is there to use null instead of undefined in JavaScript?

Question

I\'ve been writing JavaScript for quite a long time now, and I have never had a reason to use null. It seems that undefined is always preferable an

Answer 1

DOM nodes and elements are not undefined, but may be null.

• The nextSibling of the last child of an element is null.

• The previousSibling of the first child is null.

• A document.getElementById reference is null if the element does not exist in the document.

But in none of these cases is the value undefined; there just is no node there.