Javascript function overriding, Part 1

Disclaimer : All the javascript code, explaination and description in this blog series is particular to Internet Explorer only.

In Javascript, you can overide a function using the following method :

Method 1

<script language="javascript"> function foo() { alert('foo is called'); } function foo() { alert('override foo is called'); } </script>

If you call foo(), it will display 'override foo is called'.

Recently, I discover another way of overriding function :

Method 2

<script language="javascript"> function foo(yourname) { alert('Hello ' + yourname); } foo = function(yourname) { alert('(overide) Hello ' + yourname); } </script>

Both method will accomplish the same thing. However, they are semantically different.

Using method 1, what happen is the new code will over-write the existing code at the same memory address.

In method 2, the new code will be loaded into a different memory address and the function pointer foo will be changed to point to this new memory address.

What does this mean ? I will give an example and show you how to prove what I say in my next post.