Javascript OOP - 继承和原型设计(Javascript OOP - inheritance and prototyping)

 我试图在Javascript中使用OOP继承和原型设计。 请你看看我的JSfiddel http://jsfiddle.net/Charissima/daaUK/ 。 最后一个值是问题，谢谢。 我无法理解为什么带有raceCar的函数驱动器没有得到totalDistance，每个putTotalDistance设置一个。 
 
        function Car () {
            var that = this;

            this.totalDistance = 0;

            this.putTotalDistance = function(distance) {
                that.totalDistance = distance;
            };

            this.getTotalDistance = function() {
                return this.totalDistance;      
            };  

            this.drive = function(distance) {
                that.totalDistance += distance;     
                return that.totalDistance;
            };

            this.privateFunc = function() { 
                return 'car ' + this.totalDistance;
            };
        };


        function RaceCar (initialDistance) {
            var that = this;

            this.prototype = new Car();
            this.drive = function(distance) {
                return that.prototype.drive(2*distance);
            };

            this.privateFunc = function() {
                return 'raceCar ' + that.getTotalDistance();
            };
        };


        RaceCar.prototype = new Car();

        car = new Car;
        raceCar = new RaceCar;          


        car.putTotalDistance(200);
        alert('car totalDistance = ' + car.drive(10) + ' - ok');

        raceCar.putTotalDistance(200);
        alert('raceCar totalDistance before drive = ' + raceCar.getTotalDistance() + ' - ok');
        alert('raceCar totalDistance after drive = ' + raceCar.drive(10) + ' Why not 220?');                

I'm trying to use OOP in Javascript with inheritance and prototyping. Would you please have a look at my JSfiddel http://jsfiddle.net/Charissima/daaUK/. The last value is the problem, thank you. I cannot understand why the function drive with raceCar doesn't get the totalDistance, which a set per putTotalDistance.
 
        function Car () {
            var that = this;

            this.totalDistance = 0;

            this.putTotalDistance = function(distance) {
                that.totalDistance = distance;
            };

            this.getTotalDistance = function() {
                return this.totalDistance;      
            };  

            this.drive = function(distance) {
                that.totalDistance += distance;     
                return that.totalDistance;
            };

            this.privateFunc = function() { 
                return 'car ' + this.totalDistance;
            };
        };


        function RaceCar (initialDistance) {
            var that = this;

            this.prototype = new Car();
            this.drive = function(distance) {
                return that.prototype.drive(2*distance);
            };

            this.privateFunc = function() {
                return 'raceCar ' + that.getTotalDistance();
            };
        };


        RaceCar.prototype = new Car();

        car = new Car;
        raceCar = new RaceCar;          


        car.putTotalDistance(200);
        alert('car totalDistance = ' + car.drive(10) + ' - ok');

        raceCar.putTotalDistance(200);
        alert('raceCar totalDistance before drive = ' + raceCar.getTotalDistance() + ' - ok');
        alert('raceCar totalDistance after drive = ' + raceCar.drive(10) + ' Why not 220?');                

原文：https://stackoverflow.com/questions/19431042