Mixins

function createMixins() {
    function computerQualityMixin(classToExtend) {
        function attach() {
            this.getQuality = function () {
                return (this.processorSpeed_Ghz + this.ram_Gb + this.hardDiskSpace_Tb) / 3;
            };

            this.isFast = function () {
                return this.processorSpeed_Ghz > (this.ram_Gb / 4);
            };

            this.isRoomy = function () {
                return this.hardDiskSpace_Tb > Math.floor(this.ram_Gb * this.processorSpeed_Ghz);
            };
        }
        attach.call(classToExtend.prototype);
    }

    function styleMixin(classToExtend) {
        function attach() {
            this.isFullSet = function () {
                return this._keyboard.manufacturer === this._monitor.manufacturer;
            };

            this.isClassy = function () {
                let batteryLifeCondition = this._battery.expectedLife >= 3;
                let colorCondition = ["Silver", "Black"].includes(this.color);
                let weightConition = this.weight < 3;

                return batteryLifeCondition && colorCondition && weightConition;
            }
        }

        attach.call(classToExtend.prototype);
    }

    return{
        computerQualityMixin,
        styleMixin
    }
}