Solution for Mars Rovers

Mars Rovers

function MarsRover(x, y) {
    max_x = x;
    max_y = y;
    rovers = [];
    var _checkLanding = function() {
        r = rovers[0];
        if (r && (r.x > max_x || r.x < 0 || r.y > max_y || r.y < 0)) {
            console.log("Rover couldn't land.");
            rovers.shift();
            return false;
        }
    };
    var _crashTest = function() {
        r = rovers[0];
        if (r && (r.x > max_x || r.x < 0 || r.y > max_y || r.y < 0)) {
            console.log("Rover crashed Jim.");
            return false;
        }
    };
    var _move = function() {
        r = rovers[0];
        switch (r.v) {
            case "N":
                r.y++
                break;
            case "E":
                r.x++
                break;
            case "S":
                r.y--
                break;
            case "W":
                r.x--
                break;
        }
        _crashTest();
    };
    var _turnLeft = function() {
        r = rovers[0];
        switch (r.v) {
            case "N":
                r.v = "W";
                break;
            case "E":
                r.v = "N";
                break;
            case "S":
                r.v = "E";
                break;
            case "W":
                r.v = "S";
                break;
        }
    };
    var _turnRight = function() {
        r = rovers[0];
        switch (r.v) {
            case "N":
                r.v = "E";
                break;
            case "E":
                r.v = "S";
                break;
            case "S":
                r.v = "W";
                break;
            case "W":
                r.v = "N";
                break;
        }
    };
    this.addRover = function(x, y, v) {
        rovers.unshift({
            x: x,
            y: y,
            v: v
        });
        _checkLanding();
    };
    this.sendCommand = function(commandstring) {
        cs = new String(commandstring);
        for (var i = 0; i < cs.length; i++) {
            switch (cs[i]) {
                case "L":
                    _turnLeft();
                    break;
                case "R":
                    _turnRight();
                    break;
                case "M":
                    _move();
                    break;
            }
        };
    };
    this.getFinalPositions = function() {
        for (var i = rovers.length - 1; i >= 0; i--) {
            r = rovers[i];
            console.log(r.x, r.y, r.v);
        };
    }
}

var marsRover = new MarsRover(5, 5);

marsRover.addRover(1, 2, 'N');

marsRover.sendCommand('LMLMLMLMM');

marsRover.addRover(3, 3, 'E');

marsRover.sendCommand('MMRMMRMRRM');

marsRover.getFinalPositions();