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Asked: 2026-06-12T16:17:41+00:00

I wrote the following test code, I want obj.my().showTxt() to display test1, but nothing

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I wrote the following test code, I want obj.my().showTxt() to display “test1”, but nothing is displayed, what error did I make?
Thanks!

<html>
<body>
Primitive and String Objects
<script type="text/javascript">

    function Class1() {
        this.showTxt = function () { alert(this.name) }
    }

    Object.prototype.my = Class1;

    var obj = new Object();
    obj.name = "test1";

    obj.my().showTxt();

</script>

</body>
</html>
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1 Answer

  1. Editorial Team

    It seems like the problem is that your function Class1 was not returning an instance of itself.

    Is this close to what you were trying to achieve? 

    function Class1() {
    this.show = function() {
        alert('test');
    }

    return this;
}

Object.prototype.my = Class1;

var obj = new Object();

obj.my().show();

    http://jsfiddle.net/a4ZgF/

    The function Class1 returns undefined (as it has no return statement). Therefore Object.prototype.my is equal to undefined which does not have a function called showTxt(). By return this you have now returned the object which has that function on it.

    Using your browser’s debugger will help a lot to step through each line and see what is going on.

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