function checkReg() {
  for (let i = 0; i <= 6; i+= 3) {
    for (let j = 0; j <= 6; j+= 3) {
      var tempArr = [];
      let x = i;
      for (x; x < i + 3; x++) {
        let y = j;
        for (y; y < j + 3; y++) {
          tempArr.push(grid[x][y])
        }
      }
      console.log(tempArr);
    }
  }
}