How to show loading icon while processing ?

Question

Hii all;

 

I am not using ajax call simply i am calling a java script method not developed by me,

That means that java script method developed by some one else and i don't know what are the process what he doing inside this method.

The problem is while calling the method it taking some time to give the result so at that time i want to show processing icon and when the data comes then processing icon will be disable like ajax call; so any idea how to implement this.

 

Here is my code what i am doing :-

var result = getAlldata(Id, VoucherNo);
if(result.data!=null){  //Here to get result data it taking few times.
//doing some thing inside the page.
}

 Regards:

Suryakant.