Question

var print = function(text){
  document.write(text);
  document.write("</br>");
}

var A = function(){
}
A.prototype.name="A";

var B = function(){
}
B.prototype = new A();
B.prototype.name="B";

var C = function(){
}
C.prototype = new B();
C.prototype.name="C";

obj = new C();
print(obj.name);
print(obj.constructor.prototype.name);
print(obj.constructor == A);

This code gives next output:

C
A
true

Why obj.constructor here is A and not C ?

Answer 1

As seen in this code sample, you have to manually reset the .constructor property when using inheritance, or your constructor is being overridden when you call new A() or new B():

B.prototype = new A();
B.prototype.constructor = B; // need this line to fix constructor with inheritance

Here is a working sample: http://jsfiddle.net/93Msp/.

Hope this helps!