build-extend.js

function SuperType (name) {
	this.name = name;
	this.colors = ['red','blue','green'];
}
SuperType.prototype.sayName = function () {
	console.log(this.name);
}

function SubType(name,age) {
	SuperType.call(this,name);
	this.age = age;
}

SubType.prototype = new SuperType();
SubType.prototype.sayAge = function () {
	console.log(this.age);
}

var instance = new SubType("bazi",22);
console.log(instance);