Make a javascript function be called when the value after hash changes

Question

How do I call a javascript function every time the URL has a change with the string after the hash?

for example .com/onepage/

(onwindowload called)

.com/#1000

(need a function to be called)

.com/#500

(need a function to be called)

Answer 1

Here is a way......

window.location.watch(
    'hash',
    function(id,oldVal,newVal){
        console.log(oldval+" to "+newVal);
        //Do something.........
    }
);