Question

Let’s say you have a Javascript function that calls a web service method. So that webservice completes and calls a callback function, which has the result.

How do I get that result back into the original function that called the web service method? Essentially, I’m trying to “synchronize” an asynchronous call.

Update:

This is what I’m trying to do. I’m validating based on the return value of a web service.

$.validator.addMethod("zzz",
    function(value, element) {

        // Call web service function using ASP.NET Ajax.
        // Get callback value to determine validity.

        return this.optional(element) || ***return t/f based on validity***;
    },
    function(value, element) { return msg; }
);

so I guess I could do this instead:

$.validator.addMethod("zzz",
    function(value, element) {

         $.ajax({
              async: false
              url: **** web service url ****
              success: set t/f to validity var
         });

        return this.optional(element) || ***return t/f based on validity var***;
    },
    function(value, element) { return msg; }
);

Answer 1

Since you’re using jQuery, you can use async:false in your ajax command, like this:

$.ajax({
  //options..
  async: false
});
//this code will run after the request returns

Note though, this blocks the UI (locks up the browser), it’s better to continue the work that depends on the result in the success callback, like this:

$.ajax({
  //options..
  success: function(data) {
    doSomethingWithResult(data);
  }
});