MCTS - function to find best next action for current state and player

findnextaction.js

findNextAction(board, player, iterations) {
  let root = new Node();
  root.state = new NodeState();
  root.state.board = board;
  root.state.player = 3 - player;//Opponent player is owner of root node

  for (let i=0; i < iterations; i++) {
      //1.Selection
      let node = this.selectPromisingChild(root);

      //2.Expansion
      if(!node.state.isTerminal && !node.isFullyExpanded) {
          //Single node expansion
          node = node.expand();
      }

      //3.Simulation
      let result = this.simulate(node);

      //4.Update
      this.backpropagate(node, result);
  }

  let winnerNode = root.childWithMostVisits;			
  return winnerNode.state.action;
}