Question

In javascript how can I know which object I inehrit?
for example

function a() {
    this.c = 1;
}

function b() {
    this.d = 2;
}
b.prototype = new a();​

How can I check that b inherit from a?

Thank you.

Answer 1

Use the instanceof operator:

//capital letters indicate function should be used as a constructor
function A() {...}
function B() {...}
B.prototype = new A();
var a,
    b;
a = new A();
b = new B();

console.log(a instanceof A); //true
console.log(a instanceof B); //false
console.log(b instanceof A); //true
console.log(b instanceof B); //true
console.log(B.prototype instanceof A); //true