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Editorial Team
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Asked: 2026-06-01T09:39:34+00:00

I’m writing the javascript on FireFox 11 with a text editor. In the follow

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I’m writing the javascript on FireFox 11 with a text editor. In the follow case, “var n=this.val” becomes “undefined”. How to get the local value in the original class object?

<html>
<body>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script>
var Test = {
    val : 0,
    begin: function(v){
        this.val = v;
        this.recieve();
    },
    complete: function(o){
        var n = this.val;   // undefined
    },
    recieve : function(){
        $.ajax({
            url : "http://www.yahoo.com/",  // Dummy
            type: "POST",
            dataType: "json",
            complete: this.complete,
            timeout: 1000,
        });
    },
};

var c = Object(Test);
c.begin(10);
</script>
</body>
</html>
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1 Answer

  1. Editorial Team

    Because complete is a callback the scope has changed and this doesn’t refers to the object called Test. You only need to replace this with Test in the complete function:

        var n = Test.val;

    === UPDATE ===

    Your question was “How to get the local value in the original class object?”. My answer shows you how to get the field of your static object.

    If you need a shared object you should change the structure to:

    function Test() {
    var self = this;
    this.begin = function(v) {
        this.val = v;
        this.recieve();
    }
    this.complete = function(o) {
        var n = this.val;
    }
    this.recieve = function() {
        $.ajax({
            url : "http://www.yahoo.com/",  // Dummy
            type: "POST",
            dataType: "json",
            complete: function(data) {
                self.complete(data);
            },
            timeout: 1000,
        });
    }
}

    Now you can create two different objects:

    var c2 = new Test2;
c2.begin(10);
var d2 = new Test2;
d2.begin(20);
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