Question

I got acquainted with jQuery a few days back and am beginning to realize the little magic it can do.

I am curious to know how exactly a callback with arguments is executed in jQuery i.e. what is the exact execution sequence?

I went through the link http://docs.jquery.com/Tutorials:How_jQuery_Works

and it speaks of a wrong way i.e.

$.get('myhtmlpage.html', myCallBack(param1, param2));

and a right way i.e.

$.get('myhtmlpage.html', function(){
  myCallBack(param1, param2);
});

In the first case, myCallBack would be executed first and then its return value would act as an argument to get. In the latter method, get would return a web page which would be acted upon by the myCallBack.

How does it work as syntactically both have myCallBack as being still an argument to get? I’m a bit confused on this.

cheers

Answer 1

This is indeed quite a vague example. You should write:

$.get('myhtmlpage.html', function(param1, param2){
  myCallBack(param1, param2);
});

That is because internally jQuery does something like this(very simplified):

$.get = function(url, callback){
  //make call to url
  //when completed execute callback:
  callback(param1, param2);
}

You could also write:

$.get('myhtmlpage.html', myCallBack);

That will also call myCallBack with the two parameters.