Solution to level 12 in Untrusted: http://alex.nisnevich.com/untrusted/

untrusted-lvl12-solution.js

/*
 * robotNav.js
 *
 * The green key is located in a slightly more
 * complicated room. You'll need to get the robot
 * past these obstacles.
 */

function startLevel(map) {
    // Hint: you can press R or 5 to "rest" and not move the
    // player, while the robot moves around.

    map.placePlayer(0, map.getHeight() - 1);
    var player = map.getPlayer();

    map.defineObject('robot', {
        'type': 'dynamic',
        'symbol': 'R',
        'color': 'gray',
        'onCollision': function (player, me) {
            me.giveItemTo(player, 'greenKey');
        },
        'behavior': function (me) {
            me.running = me.running || false;
            me.startX = me.startX || undefined;
            me.startY = me.startY || undefined;
            var getDirection = function(x1,y1,x2,y2) {
                var dx = x2 - x1;
                var dy = y2 - y1;
                if(dy > 0) {
                    return 'up';
                } else if (dy < 0) {
                    return 'down';
                }
                if(dx > 0) {
                    return 'left';
                } else if (dx < 0) {
                    return 'right'
                }    
            }
            var trackPlayer = function() {
                me.startX = player.getX();
                me.startY = player.getY();
            }
            player.setPhoneCallback(function() {
                me.running = !me.running;
                
            });
            if(me.running === true) {
                var direction = getDirection(
                player.getX(), player.getY(), me.startX, me.startY
                );
                me.move(direction);       
            }
            trackPlayer();
            
            
            
            
            
            






        }
    });

    map.defineObject('barrier', {
        'symbol': '░',
        'color': 'purple',
        'impassable': true,
        'passableFor': ['robot']
    });

    map.placeObject(map.getWidth() - 1, map.getHeight() - 1, 'exit');
    map.placeObject(1, 1, 'robot');
    map.placeObject(map.getWidth() - 2, 8, 'greenKey');
    map.placeObject(map.getWidth() - 2, 9, 'barrier');

    for (var x = 0; x < map.getWidth(); x++) {
        map.placeObject(x, 0, 'block');
        if (x != map.getWidth() - 2) {
            map.placeObject(x, 9, 'block');
        }
    }

    for (var y = 1; y < 9; y++) {
        map.placeObject(0, y, 'block');
        map.placeObject(map.getWidth() - 1, y, 'block');
    }

    for (var i = 0; i < 4; i++) {
        map.placeObject(20 - i, i + 1, 'block');
        map.placeObject(35 - i, 8 - i, 'block');
    }
}

function validateLevel(map) {
    map.validateExactlyXManyObjects(1, 'exit');
    map.validateExactlyXManyObjects(1, 'robot');
    map.validateAtMostXObjects(1, 'greenKey');
}

function onExit(map) {
    if (!map.getPlayer().hasItem('greenKey')) {
        map.writeStatus("We need to get that key!");
        return false;
    } else {
        return true;
    }
}