json和php的ajax调用问题

Question

i have one AJAX function getting results from php file as bellow

$.ajax({
             type: "POST",
             url: "GeteT.php",
             cache:false,
             data:"id="+ encodeURIComponent(1),
             dataType:'json',
             success: function(json)
             {
         g_foo = json.foo;
         }
        });

now i want to use the value of g_foo but i can't i try using console.log but i am facing strange problem. like

if i use function like that

       $.ajax({
         type: "POST",
         url: "GeteT.php",
         cache:false,
         data:"id="+ encodeURIComponent(1),
         dataType:'json',
         success: function(json)
         {
     g_foo = json.foo;
        console.log(g_foo);
     }
    });

now i can see the value return from php file

if now i use function like that

         $.ajax({
         type: "POST",
         url: "GeteT.php",
         cache:false,
         data:"id="+ encodeURIComponent(1),
         dataType:'json',
         success: function(json)
         {
     g_foo = json.foo;

     }
    });
        console.log(g_foo);

now i got error undefined g_foo;

thanks

Answer 1

As ajax is asynchronous, there's no way of making sure that g_foo is available as soon as you call the $.ajax() request, hence it's not available outside that callback.

You could however, specify async:false to that .ajax() call, but it will most likely block the browser, attempting to wait for the request, something I don't think you want to happen.