代码重构。 在类的所有实例上运行的方法

Question

I have a class constructor whose main work is to instantiate Objects. It takes ID, checks that object with such ID was not created before and creates it.

function Vehicle(ID){
    if (this.listOfVehicles.indexOf(ID) !== -1) throw new Error('Vehicle with such ID already exists');
    this.ID = ID;
    this.listOfVehicles.push(ID);
    this.isMoving = true;
}

Prototype of the object has the storage of all the object IDs and two methods run - which makes the vehicle moving and stopAll, which stops all vehicles.

Vehicle.prototype = {
    'listOfVehicles' : [],
    'run'            : function(){
        this.isMoving = true;
    },
    'stopAll'           : function(){
        var vehicleID, i, listOfVehicles = Vehicle.prototype.listOfVehicles;
        for(i = 0; i < listOfVehicles.length; i++){
            vehicleID = listOfVehicles[i];
            vehicles[vehicleID].isMoving = false;
        }
    }
};

Basically everything is working nicely:

var vehicles = {};
vehicles[3] = new Vehicle(3);
vehicles[6] = new Vehicle(6);
vehicles[12] = new Vehicle(12);

All vehicles are instantiated and moving

vehicles[3].stopAll();

All vehicles are not moving

vehicles[3].run();

only vehicle 3 i moving

There is one thing, I do not like here. In order to stop all vehicles I need to use method from some of the vehicles. But I can not think of any better way of doing it.

Answer 1

You can define:

Vehicle.stopAll = function () {
    var vehicleID, i, listOfVehicles = Vehicle.prototype.listOfVehicles;
    for(i = 0; i < listOfVehicles.length; i++){
        vehicleID = listOfVehicles[i];
        vehicles[vehicleID].isMoving = false;
    }
}

There's actually nothing requiring you to attach this function to the class, you could also define it as:

function stopAllVehicles () {
    var vehicleID, i, listOfVehicles = Vehicle.prototype.listOfVehicles;
    for(i = 0; i < listOfVehicles.length; i++){
        vehicleID = listOfVehicles[i];
        vehicles[vehicleID].isMoving = false;
    }
}

because Javascript classes don't implement information hiding (you can do that yourself by enclosing information in local variables of functions).

Or you can use your original class definition, and use Vehicle.prototype.stopAll() . Since JS uses prototype-based OO, there's always a vehicle available to call the method on.