使用jquery和php的ajax

Question

I have a input field with id age. I am trying to pass this age and some other values from other input fields using ajax as follows-

var age = document.getElementById('age').value;
var wpm = document.getElementById('wpm').value;
var sex = document.getElementById('sex').value;
var queryString = "?age=" + age ;

queryString +=  "&wpm=" + wpm + "&sex=" + sex;
ajaxRequest.open("GET", "ajax-example.php" + queryString, true);
ajaxRequest.send(null); 
ajaxRequest.open("GET", "ajax-example.php" + queryString, true);

so in my javascript part of my html document if i write

var age = document.getElementById('age').value;

the program executes perfectly.

But if i write this instead of the above statement -

var age =$('#age').val();

My age value is not passed

So my question is what is the differnece between the statements

var age = document.getElementById('age').value;
var age =$('#age').val();

Answer 1

Javascript

 var age = document.getElementById('age').value;

Jquery

var age =$('#age').val();

If $("#age").val() is not working then odds are that you don't have the libraries loaded for jquery at all

http://code.jquery.com/jquery-latest.min.js

Is for the latest jquery libraries. If you load that library into your page than all jquery scripts and functions should work which I'm fairly positive ajax is a jquery function so you'll want to do that