I am newbie in Javascript i am trying to add some function in object prototype which is created by Object.prototype i tried this code
var a=function(){this.k="yes";}
a.prototype.b1=function(){console.log("function of a");};
var b=Object.create(a.prototype);
b.prototype.c1=function(){console.log("function of b");};
b.c1();
Its giving me error 'Cannot set property 'c1' of undefined' I am not getting where i am doing mistake kindly guide me . Thanks in advance
I'm not sure what exactly you were trying to do, but currently your problem is that b is a plain object (which inherits from a.prototype that has .b1 and .constructor properties) with no b.prototype property. Nonetheless you're trying to set an property on that non-existing thing.
You either were looking for
var a = {
b1: function(){console.log("function of a");}
};
var b = Object.create(a);
b.c1 = function(){console.log("function of b");};
b.c1();
b.b1();
with no constructor functions or .prototype properties involved - just plain prototype inheritance - or you were looking for
function A() { this.k="yes"; }
A.prototype.b1 = function(){console.log("function of A.prototype");};
function B() { A.call(this); }
B.prototype = Object.create(a.prototype);
B.prototype.c1 = function(){console.log("function of B.prototype");};
var b = new B();
b.c1();
b.b1();
which is a typical example of inheritance between "class" structures, i.e constructors with accompanying prototype objects. You had forgotten to make B a function and instantiate it before calling a method.
Your code should be like this:
var a=function(){this.k="yes";};
a.prototype.b1=function(){console.log("function of a");};
var b =function(){};
b.prototype=new a();
b.prototype.c1=function(){console.log("function of b");};
var bObj = new b();
bObj.c1()
You're trying to achieve two separated things here.
First :
var b=Object.create(a.prototype);
I assume that you're trying to extend a class in b. Consider modifying directly the b prototype after you created it :
//Create b class
var b = function(){this.key = 2};
//Extends a in b
var b.prototype = new a();
Second :
b.prototype.c1=function(){console.log("function of b");};
b.c1();
You're trying to call your function from your class with b.c1();. Try to instanciate it first in another variable var bObject = new b(); and then call the function assigned to te prototype : bObject.c1()
Your overall code should look like this :
//Create a class here
var a=function(){this.k="yes";};
//assign b1 function to a class
a.prototype.b1=function(){console.log("function of a");};
//Create b class
var b = function(){this.key = 2};
//extends a in b
b.prototype = new a();
//create c1 function in b class
b.prototype.c1=function(){console.log("function of b");};
//create bObj from b class
var bObj = new b();
//call c1 function defined in b class
bObj.c1();
//can also call b1 function from a class
bObj.b1();
b.prototype = new a();b function, and your var b.prototype declaration is invalid as well.
b) also, you can't dovar bObj = new b(), as b isnt a constructor.bis made a function that creates instances and has a.prototype…