javascript – 如何在for循环中调用ajax函数

参见英文答案 > JavaScript closure inside loops – simple practical example                                    39个
我是ajax和JavaScript的新手.
我想要做的是多次调用一个ajax函数从资源中获取某些数据,然后将所有数据“推”到一个数组中,这样我以后就可以在代码中使用它了.这是我的代码.

var arr = [];
var users = ["brunofin","comster404","ESL_SC2","OgamingSC2","cretetion","freecodecamp","storbeck","habathcx","RobotCaleb","noobs2ninjas"];

for (i = 0; i < users.length; i++) {
    $.ajax({
        url: "https://api.twitch.tv/kraken/streams/" + users[i],success: function(data) {
            arr.push(data);
        },error: function(data) {
            arr.push("blank");
        },complete: function() {
            if (i == users.length) {
                console.log(arr); //This seem to print even when the condition isn't true
            }
        }
    });
}

代码的问题在于,即使i不等于users.length,它也会打印到控制台

我的问题是;在打印到控制台之前,如何确保等待i == users.length为真？
请记住,我仍然希望该过程是异步的.

解决方法

以下是如何在不对另一个请求运行的情况下调用所有请求而考虑其成功：

var arr = [];
var users = ["brunofin","noobs2ninjas"];

var runRequests = function(userIndex) {
  if (users.length == userIndex) {
    console.log("runRequests Success",arr);
    return;
  }

  var user = users[userIndex];

  $.ajax({
    url: "https://api.twitch.tv/kraken/streams/" + user,success: function(data) {
      arr.push(data);
    },error: function() {
      arr.push({});
      console.error("runRequests Error","user",arguments);
    },complete: function() {
      runRequests(++userIndex);
    }
  });
};

runRequests(0);

Working demo