Problems with basic prototyping in Javascript

Question

i am kinda new to javascript and i started off on something where i am stuck with some basics, the thing is i am trying to create an prototype for an object and then the references of created objects in an array and then accesing their methods but i am wrong somewhere can anyone help me with this, what i am doing is shown here :-

function Obj(n){
    var name=n;
}
Obj.prototype.disp = function(){
    alert(this.name);
};
var l1=new Obj("one");
var l2=new Obj("two");
var lessons=[l1,l2];
//lessons[0].disp();
//alert(lessons[0].name);

but none of these methods seem to work out.... :(

Sirko · Accepted Answer · 2013-07-29 13:55:19Z

6

You not assigning a property of the Obj object, but just have a local variable inside the constructor. Change like this:

function Obj(n){
    this.name = n;
}

Example Fiddle

answered Jul 29, 2013 at 13:55

Sirko

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1 Comment

Mangiucugna Over a year ago

You posted the same solution 7 seconds before me :) +1

Mangiucugna · Accepted Answer · 2013-07-29 13:55:26Z

6

Your problem is with the constructor, you are assigning the parameter to a local variable not to a field variable, change it like:

function Obj(n){
    this.name=n;
}

Hope this helps

answered Jul 29, 2013 at 13:55

Mangiucugna

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2 Comments

Harshit Laddha Over a year ago

thanks a lot i completely forgot that , it works thank you very much

Sirko Over a year ago

@user1860959 If an answer solved your problem, mark it as such by clicking the checkmark right next to it (upper left).

HIRA THAKUR · Accepted Answer · 2013-07-29 14:10:24Z

1

Use this:

 function Obj(n){
        this.name=n;
    }

REASON:

Difference between var name=n; and this.name=n;

var name=n;

The variable declared with var is local to the constructor function. It will only survive beyond the constructor call if it's used in some method inside the object

this.name=n;

this is property of the object, and it will survive as long as the object does, irrespective of whether it's used or not.

Example:this in javascript

answered Jul 29, 2013 at 14:10

HIRA THAKUR

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