1function Class () {}
2Class.prototype.calc = function (a, b) {
3 return a + b;
4}
5
6// Create 2 instances:
7var ins1 = new Class(),
8 ins2 = new Class();
9
10// Test the calc method:
11console.log(ins1.calc(1,1), ins2.calc(1,1));
12// -> 2, 2
13
14// Change the prototype method
15Class.prototype.calc = function () {
16 var args = Array.prototype.slice.apply(arguments),
17 res = 0, c;
18
19 while (c = args.shift())
20 res += c;
21
22 return res;
23}
24
25// Test the calc method:
26console.log(ins1.calc(1,1,1), ins2.calc(1,1,1));
27// -> 3, 3