javascript - 使用 ajax 上下文不能解决范围问题

Question

我无法使 ajax 上下文工作:-

var msgdata = "";
$.ajax({
  type: "POST",
  url: "players/" + joinplayer + "/joingame.php",
  data: { 
    userID: "<?php echo $_SESSION['username']; ?>",
    gameinfo: JSON.stringify(<?php echo json_encode($_SESSION['profile']['user'], true); ?>)
  },
  context: msgdata,
  success: function(data) {
    msgdata = data;
    $.ajax({
      type: "POST",
      url: "renamejoin.php",
      data: { 
        userID: "<?php echo $_SESSION['username']; ?>",
        joinID: joinplayer
      },
      context: msgdata,
      success: function(data) {
        if (data == "" && msgdata != "") {
          // sucessfully joined a player's game
        } else {
            alert(data);
        }
      },
      error: function() {   
        alert(joinplayer + "'s game is no longer available.");
      }
    });
  },
  error: function() {
    alert(joinplayer + "'s game is no longer available.");
  }
});
if (msgdata == "");
  // start showing games awaiting players again
  gamefeedrefresh;
  timer = window.setInterval(gamefeedrefresh, 2500);
}

msgdata 在此最终 if 语句中始终为 ""。问题似乎是一个范围问题，但即使是一个或两个上下文语句也没有区别。

是否可以解决此范围问题？感谢所有建议。

Answer 1

Ajax 请求是异步的，这意味着程序的其余部分将在请求返回之前执行。如果要在请求完成后运行代码，请将其移动到 success 函数体中。

您可能还想看看 Promise .