jQuery AJAX callback

Question

I'm having a difficult time trying to get this javascript function to return false inside of a .post() function.

Is this even possible? or is there another way to do a simple ajax check to validate the voucher code is in the database.

function check_options(){       
        var voucher_code = $('#voucher_code').val();
        $.post(baseURL+"ajax.php", { tool: "vouchers", action: "check_voucher", voucher_code: voucher_code },
            function(data) {
            if(data == 'invalid'){
                // NEED TO RETURN FALSE FOR THE MAIN FUNCTION
            }
        });

}

Have you thought about using a jQuery form validation plugin such as jquery.validate? — GordonM
– GordonM, Commented Jun 1, 2011 at 17:59

Robert · Accepted Answer · 2011-06-01 17:58:53Z

4

You can't return false for the main function because it's already processed by the time the ajax call completes. You'll need to use callbacks.

function check_options(callback) {
    var voucher_code = $('#voucher_code').val();
    $.post(baseURL + "ajax.php", {
        tool: "vouchers",
        action: "check_voucher",
        voucher_code: voucher_code
    }, function(data) {
        if (data == 'invalid') {
            callback && callback(false);
        } else {
            callback && callback(true);
        }
    });

}

check_options(function(result) {
    // Handle True/False based on result
});

answered Jun 1, 2011 at 17:58

Robert

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Comments

carlosfigueira · Accepted Answer · 2011-06-01 17:58:26Z

2

You can't return false for the main function, because the post call is asynchronous. The function will return immediately after the $.post call, now when the response arrives. When the network call returns, then the function passed in the parameter will be invoked, but at that point the main function will have been long finished.

Basically, you're trying to do a synchronous network call, and there is no way to do that in JS.

answered Jun 1, 2011 at 17:58

carlosfigueira

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1 Comment

Robert Over a year ago

You can make synchronous network calls, it's just a terrible idea.

Trey · Accepted Answer · 2011-06-01 18:01:10Z

0

function check_options(){       
  var voucher_code = $('#voucher_code').val();
  $.ajax({
    type: 'POST',,
    url: baseURL+"ajax.php",
    data: { tool: "vouchers", action: "check_voucher", voucher_code: voucher_code },
    success: function(msg){
      alert('Success!');
    },
    error:function(e){
      alert('Fail!');
    }
  });
}

answered Jun 1, 2011 at 18:01

Trey

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Comments

DarthJDG · Accepted Answer · 2011-06-01 21:00:22Z

0

The $.post is asynchronous as mentioned. As such, the function where you want to return false is actually executing after the main function (check_options) completes execution (and returns). I would suggest modifying your flow of control to account for an asynchronous call, or make the call synchronous (there should be an additional param, "async" I believe).

$.post({async:false, ...);

edited Jun 1, 2011 at 21:00

DarthJDG

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answered Jun 1, 2011 at 18:01

aepheus

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