[jQuery] Best way to switch code between pages

[galen]

I have a header file that includes the jquery.js and a custom.js in
all of my pages.  In the custom.js what is the best way to switch
between current pages.

For example if index page loads do this if contact page loads do
that.  i have a unique id in the body of each page. But can't seem to
find a way to use this.

if ($("#home")) {
        $(document).ready(function(){
        });
}

Doesn't work, an object is returned regardless.

I'm sure i can figure out a way eventually. just curious what the best
way would be.

Thanks.