array inheritance question in javascript

Question

function ClassA() { this.a=[]; this.aa=100; }
function ClassB() {  }

ClassB.prototype = new ClassA;
ClassB.prototype.b=function(){return "classbb"};

for (var l in ClassB.prototype){

    Array.prototype[l] = ClassB.prototype[l]; 
}
var array1 = [];
alert(array1.b());

Can

Array.prototype[l] = ClassB.prototype[l]

be replaced by

Array.prototype[l] = ClassB[l]

? Could someone help me? Thanks.

wong2 · Accepted Answer · 2011-03-25 12:22:09Z

2

No, you can't.ClassB has no property b, ClassB.prototype has.
If you do, in alert(array1.b()); array1.b will be undefined

edited Mar 25, 2011 at 12:22

answered Mar 25, 2011 at 12:11

wong2

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6 Comments

jsnewman Over a year ago

@wong2. If I want to define ClassB.b, how should I do? Thanks

wong2 Over a year ago

@jsnewman I'm not sure if I understand what you want to do...You can define ClassB.b by function ClassB() {}; ClassB.b = function(){return "classbb"};

jsnewman Over a year ago

@wong2: Could you tell me the difference between ClassB.b and ClassB.prototype.b? Thank you very much. And what does ClassB.property mean?

wong2 Over a year ago

@jsnewman If you define ClassB.prototype.b to some value, then every instance created by new ClassB();(like var class_b = new ClassB();) will have a property b, but if you define ClassB.b, then b is just a property of ClassB(who is a function, and also an object).Is that clear?

jsnewman Over a year ago

@wong2: function ClassB() { this.b = function(){return "classbb"}; } ClassB.b = function(){return "classBB"}; What is the difference between this.b and ClassB.b?

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