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Mars Rover kata in JavaScript: implementation
function MarsRover(location, direction, grid, obstacles) {
self = this;
this.location = (location === undefined) ? [0, 0] : location;
this.direction = (direction === undefined) ? 'N' : direction;
this.grid = (grid === undefined) ? [100, 100] : grid;
this.obstacles = (obstacles === undefined) ? [] : obstacles;
this.status = 'OK';
this.commands = function(commands) {
if (commands === undefined) { // Getter
return this.commandsArray;
} else { // Setter
for(var index = 0; index < commands.length; index++) {
var command = commands[index];
if (command === 'f' || command === 'b') {
if (!move(command)) break;
} else if (command === 'l' || command === 'r') {
turn(command);
}
}
resetLocation();
this.commandsArray = commands;
}
};
function resetLocation() {
self.location = [
(self.location[0] + self.grid[0]) % self.grid[0],
(self.location[1] + self.grid[1]) % self.grid[1]
]
}
function move(command) {
var xIncrease = 0, yIncrease = 0;
if (self.direction === 'N') {
yIncrease = -1;
} else if (self.direction === 'E') { // East
xIncrease = 1;
} else if (self.direction === 'S') { // South
yIncrease = 1;
} else if (self.direction === 'W') { // West
xIncrease = -1;
}
if (command === 'b') { // Backward
xIncrease *= -1;
yIncrease *= -1;
}
var newLocation = [self.location[0] + xIncrease, self.location[1] + yIncrease];
if (isObstacle(newLocation)) {
return false;
}
self.location = newLocation;
return true;
}
function isObstacle(newLocation) {
for(var index = 0; index < self.obstacles.length; index++) {
if (newLocation.toString() == self.obstacles[index].toString()) {
self.status = 'obstacle';
return true;
}
}
return false;
}
function turn(command) {
var directionNumber = directionAsNumber(self.direction);
if (command === 'l') { // Left
directionNumber = (directionNumber + 4 - 1) % 4;
} else { // Right
directionNumber = (directionNumber + 1) % 4;
}
self.direction = self.directions[directionNumber];
}
this.directions = ['N', 'E', 'S', 'W'];
function directionAsNumber(direction) {
for(var index = 0; index < 4; index++) {
if (self.directions[index] === direction) return index;
}
}
}
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