Question

function A(){}
var B = {};

var a1 = new A();
var a2 = new A();
var b1 = B;
var b2 = b1;

A.prototype.prop = "A's Property";
b1.prop = "B's Property";
a1.prop = "Not Prop";
alert (a1.prop + " not equal to " + a2.prop);
b2.prop = "Not Prop";
alert (b1.prop +" still equal to "+ b2.prop);

As you can see, b2.prop can’t pass by value, how to pass by value without changing the property name?

Answer 1

Define a clone method:

function clone(o) {
    if(!o || 'object' !== typeof o)  {
        return o;
    }
    varc = 'function' === typeof o.pop ? [] : {};
    var p, v;
    for (p in o) {
        if (o.hasOwnProperty(p)) {
            v = o[p];
            if (v && 'object' === typeof v) {
                c[p] = clone(v);
            } else {
                c[p] = v;
            }
        }
    }
    return c;
}

and then use it to clone your b1 object:

var b1 = B;
var b2 = clone(b1);