Inherit JS

inherit.js

// Makes fn inherit from parent class
// Allows "super" calls ONLY in the constructor via Class.parent(this, param1, param2, ...)
// Also allows to extend the prototype giving more arguments
function inherit(parent, fn) {
    fn || (fn = function() { });
    fn.prototype = Object.create(parent.prototype);
    for (var i = 2; i < arguments.length; ++i) {
        extend(fn.prototype, arguments[i]);
    }
    fn.prototype.constructor = fn;
    fn.parent = parent.call.bind(parent);
    return fn;
}

usage.js

function Part(vendor, model) {
    this.vendor = vendor;
    this.model = model;
}

Part.prototype = {
    getVendor: function() { return this.vendor },
    getModel: function() { return this.model }
};

function Tire(vendor, model, speed) {
    Tire.parent(this, vendor, model);
    this.speed = speed;
}

inherit(Part, Tire, {
    getSpeed: function() {
        return this.speed;
    }
});

var tire = new Tire('vendor', 'model', 100);
console.log(tire.getVendor(), tire.getModel(), tire.getSpeed());