javascript - JS : Assignment within if statment doesn't work

Question

我有一个二维数组，想要将随机元素值设置为 2。我的尝试如下，但没有成功..如果随机值未定义，则将其设置为2，如果不重复。提前致谢!

var randomTileFunction = function (board) {
  var randomTile = board[Math.floor(Math.random() * 4)][Math.floor(Math.random() * 4)];
  if(randomTile === undefined) {
    randomTile = 2;
  } else {
    randomTileFunction(board);
  }
};

Answer 1

randomTile 是一个变量，其赋值不会影响另一个变量 board[Math.floor(Math.random() * 4)][Math.floor(Math.random() * 4)].

var i = Math.floor(Math.random() * 4);
var j = Math.floor(Math.random() * 4);
if(board[i][j] === undefined) {
  board[i][j] = 2;