add random for best score candicates

app.js

@@ -379,12 +379,16 @@ function minimaxNextMove(){
  let currentPlayerMinimax = isCpuMaximizing? 'x' : 'o';
  let bestScore = isCpuMaximizing? (-Infinity) : (+Infinity);
  let move;
+ let scoreList = {};
  for (let i = 0; i < 9; i++){
  if(arrayForMinimax[i] === ''){
  arrayForMinimax[i] = currentPlayerMinimax;
  // next move is the player 1 not cpu, that's why !isCpuMaximizing
  let score = minimax(0, !isCpuMaximizing);
  arrayForMinimax[i] = '';
+ // store all score in a score list
+ scoreList[i] = score;
+ console.log("index:" + i + "score:" + score);
  if (isCpuMaximizing){
  if (score > bestScore) {
  bestScore = score;
@@ -398,7 +402,12 @@ function minimaxNextMove(){
  }
  }
  }
- return cellElements[move];
+ // list of all best candidates (they all have the best score)
+ let finalCandidates = findKeysByValue(scoreList, bestScore);
+ console.log("the final candidates:" + finalCandidates)
+ let finalMove = randomNextMove(finalCandidates);
+ console.log("final move:" + finalMove);
+ return cellElements[finalMove];
 }
 
 let scores = {
@@ -440,6 +449,16 @@ function minimax(depth, isMaximizing) {
  }
 }
 
+function findKeysByValue(map, score){
+ const keyList = [];
+ Object.keys(map).forEach(key => {
+ if (map[key] == score) {
+ keyList.push(key);
+ }
+ });
+ return keyList;
+}
+
 // check win based on minimax array
 function checkWinForminimax(currentClassInminimax) {
  return WINNING_PATTERNS.some(pattern => {