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POJavaScript's anonymous objects prototype
 

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    <p>I learn JavaScript's "OOP" models, and looking forward to an advice how can I code around some problem I faced. (I will use the terminology "instance" later however now I know there's no instances in JavaScript.) Consider the following code:</p> <pre><code>function Class1(){ this.locvar1 = "locvar1"; this.locvar2 = "locvar2"; } function Class2(){ this.set = function(){ this.locvar1 = "ch_locvar1"; } } Class2.prototype = new Class1; //we'll get two instances from Class2 var x = new Class2(); x.set(); // we'll change the x's field with that (hoping that) var y = new Class2(); // hoping that this will be a totally new instance, // and the previous set() won't change it at all </code></pre> <p>Okay that code will work the way I wanted. I create two new objects, and their prototype will be the same still after I called x.set().</p> <pre><code>x.locvar1's value: "ch_locvar1" x.locvar2's value: "locvar2" y.locvar1's value: "locvar1" y.locvar2's value: "locvar2" their prototypes value: locvar1 : "locvar1", locvar2 : "locvar2" </code></pre> <p>The problem comes, when I try to use further objects in Class1's field.</p> <pre><code>function Class1(){ this.locvar1 = {a : "a"}; this.locvar2 = "locvar2"; } function Class2(){ this.set = function(){ this.locvar1.a = "ch_locvar1"; } } Class2.prototype = new Class1; var x = new Class2(); x.set(); var y = new Class2(); </code></pre> <p>That will out:</p> <pre><code>x.locvar1.a's value: "ch_locvar1" x.locvar2's value: "locvar2" what's ok, but..: y.locvar1.a's value: "ch_locvar1" y.locvar2's value: "locvar2" their prototypes value: locvar1.a : "ch_locvar1", locvar2 : "locvar2" </code></pre> <p>So it seems like with the statement "this.locvar1.a" I change the {a : "a"} object's prototype globally, and not a local instance of "this.locvar1"... </p> <p>Am I sure on this? How can I code around that? I tried to change "this.locvar1 = new {a : "a"};" because this seems logical to me, but the result is the same.</p>
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    1. COIn javascript objects are passed by reference. This is why in the second example `locvar1` changes.
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    2. COI'm not sure what you were expecting to happen...?
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    3. COIt seems that CoffeeScript compiles this as you expect it to work: http://jsfiddle.net/nfJDk/14/
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