robot-moves.js

const dir = {
  North: { x:  0, y:  1,  R:  "East", L:  "West" },
   West: { x: -1, y:  0,  R: "North", L: "South" },
  South: { x:  0, y: -1,  R:  "West", L:  "East" },
   East: { x:  1, y:  0,  R: "South", L: "North" }
};

const moves = {
  R: ([x, y, d]) => ([x, y, dir[d].R]),
  L: ([x, y, d]) => ([x, y, dir[d].L]),
  A: ([x, y, d]) => ([x + dir[d].x, y + dir[d].y, d])
};

let start = [7, 3, "North"];
let input = "RAALALA";

let result = input.split("").reduce((pos, lra) => moves[lra](pos), start);

console.log(result);