ASP.NET: jQuery Ajax result not defined

Question

I have this jQuery ajax:

        // ... omitted code ...

        var data = "{'TagName':'" + TagName + "'}";

        var resultSet = 0;

        jQuery.ajax(
        {
            type: "POST",
            url: '<%= ResolveUrl("~/Webservices/TagWebServices.asmx/GetTagByTagName") %>',
            data: data,
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (t)
            {
                resultSet = t.d;
            }
        });

        jQuery(this).after("<div style='color:#E3E3E3; margin-bottom:10px;'>" +
        resultSet.desc +
        "</div>" );

        // ... omitted code ...

The problem is that resultSet.desc always returns "undefined" BUT when I use Firebug and add a breaking point in the last line and then click (Continue) resultSet.desc works as expected.

Welcome to the wonderful world of async! You can't do that. — SLaks
– SLaks, Commented Dec 3, 2012 at 14:37
This is the first time I use jQuery ajax but that makes sense it was a stupid mistake from my part. thanks — Eric Bergman
– Eric Bergman, Commented Dec 3, 2012 at 15:06

A. Wolff · Accepted Answer · 2012-12-03 14:38:14Z

1

Ajax is asynchronous by default. You could try to set ajax request synchronous setting: async:false, but this is a bad way.

The way to go is to code your logic in the success callback function keeping ref on 'this' object.

var data = "{'TagName':'" + TagName + "'}";

        var resultSet = 0,
            that = this;

        jQuery.ajax(
        {
            type: "POST",
            url: '<%= ResolveUrl("~/Webservices/TagWebServices.asmx/GetTagByTagName") %>',
            data: data,
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (t)
            {
                resultSet = t.d;
                 jQuery(that).after("<div style='color:#E3E3E3; margin-bottom:10px;'>" +
                    resultSet.desc +
                    "</div>" );
            }
        });

answered Dec 3, 2012 at 14:38

A. Wolff

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Comments

Samuel Caillerie · Accepted Answer · 2012-12-03 14:37:49Z

1

An ajax call is Asynchronous (by definition...). So you have to put the affectation in the success handler:

$.ajax({ ...
    success : function(t) {
        resultSet = t.d;
        jQuery(this).after("<div style='color:#E3E3E3; margin-bottom:10px;'>" +
            resultSet.desc +
        "</div>" );
    }
)};

answered Dec 3, 2012 at 14:37

Samuel Caillerie

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