我的Javascript（和Mootools）函数未返回true或false

Question

I have the following function:

function validateField(query) {
    new Request.JSON({
        onRequest  :  function() {

        },
        onSuccess : function(json){
            return true;
        },      
        data : query + '&validate=true',
        url  : base + 'ninjquiry.php'
    }).send();              
}

Now onSuccess is definitely firing because I can put a console.log in there and it works, however if I do the following somewhere else:

console.log(validateField(query));

I get "undefined". Why is this ?

Thanks for any help in advance

• Alex

Answer 1

Ajax is asynchronous . The onSuccess callback is called later, after the validateField function has been finished. The return true will vanish into thin air.

You would have to either make your call synchronous - I'm sure MooTools has a setting for it - but that is highly discouraged, as it can freeze the browser.

Or, this is the better alternative, change your code so that everything relevant happens in the onSuccess callback.