move-3.js

function move(state) {
  const head = state.you.body[0];
  const neck = state.you.body[1];
  const moves = ['up', 'down', 'left', 'right'];

  for (const move of moves) {
    const coord = moveAsCoord(move, head);
    if (!offBoard(state, coord) && !coordEqual(coord, neck)) {
      return {move: move};
    }
  }
  return {move: 'up'};
}