等待多个异步 Facebook 请求

Question

需要等待对Facebook的几个请求完成，然后才能对页面采取最终操作（更新返回信息的请求数），但不确定如何处理它。

如何在触发函数之前检查每个函数是否完整并更新计数器。
window.load为时过早，除非登录后刷新页面...？

    window.fbAsyncInit = function () {
     FB.init({
     appId: 'id', // App ID
     //channelUrl: '//facebookdev.smithbrosagency.com/LOL/xss_channel.htm', // Channel File
     status: true, // check login status
     cookie: true, // enable cookies to allow the server to access the session
     xfbml: true  // parse XFBML
     });
     getStatus();
      //Subscribe to events
     FB.Event.subscribe('auth.statusChange', function (response) { if (response.authResponse) { getStatus(); } });
     FB.Event.subscribe('auth.login', function (response) { if (response.status === 'connected') { getStatus(); } });
    };
     function getStatus() {
      FB.getLoginStatus(function (response) {
      if (response.status === 'connected') {
       setPanel('results'); // connected
       var accessToken = response.authResponse.accessToken;
       var obj = getPermissionsObject(function (permissions) {
       getUserInfo(response);
       getUserPhotos(response, accessToken);
       getFriends(response, accessToken);
       getUserLocations(response, accessToken);
       getUserMusic(response, accessToken);
       getUserMovies(response, accessToken);
           });
      } else {
       setPanel('login'); // not logged in or unauthorized
      }
      });
     }
     function getUserPhotos(response, accessToken) {
      FB.api('/me/photos?access_token=' + accessToken, function (response) {
      var photoList = response.data;
      var len = photoList.length;
      if (len >= 3) {
       var max = 3;
   if (len > max) { len = max }; // cap it at 3
   for (var i = 0; i < len; i++) {
   (function () {
    var j = i;
    var idx = i + 1;
    $('.result2 .option' + idx + ' input').val(photoList[i].picture);
    $('.result2 .option' + idx + ' img').attr("src", photoList[i].picture);
       })();
    }
       $('div.result2').addClass("active");
       $('#q2 input').val(1); // add to hidden to count results
          }
    else {
       // hide & subtract from total questions
       $('div.result2').addClass("inactive");
       $('#q2 input').val(0); 
      }
      });
     }
     $(window).load(function () {
      $.when($('#q2 input').val() != '' && $('#q4 input').val() != '' && $('#q5 input').val() != '').then(test());
      function test() {
      // calc total questions
      var total = 0;
      $("#Results div input[hidden]").each(function () {
       total += $(this).val() * 1;
      });
      alert(total);
      }
     });

Answer 1

我不确定我是否正确理解你，但似乎你需要实现这样的对象：

<script type="text/javascript">
//Monitoring object
function RequestStatusMonitor()
{
    this.resetRequests();
}
//IDs of the requests you need to monitor
RequestStatusMonitor.prototype.requests=["firstRequest","secondRequest","thirdRequest"];
//Status of the requests
RequestStatusMonitor.prototype.requestsCompleted=[];
//Set all requests to incomplete state
RequestStatusMonitor.prototype.resetRequests = function()
{
    this.requestsCompleted = [];
    for(var it in this.requests)
    {
        this.requestsCompleted[this.requests[it]] = false;
    }
}
//Set status for a request determined by requestName
RequestStatusMonitor.prototype.setRequestStatus = function(requestName, status)
{
    this.requestsCompleted[requestName] = status;
}
//Check if all requests are completed
RequestStatusMonitor.prototype.allRequestsAreCompleted = function()
{
    for(var it in this.requestsCompleted)
    {
        if(!this.requestsCompleted[it])
        {
            return false;
        }
    }
    return true;
}
//----------------------------------------------------------------------------------
//Usage Example
var monitor = new RequestStatusMonitor();
function onFirstRequestFinished(/*necessary parameters*/)
{
    monitor.setRequestStatus("firstRequest", true);
    checkCompleted();
}
function onSecondRequestFinished(/*necessary parameters*/)
{
    monitor.setRequestStatus("secondRequest", true);
    checkCompleted();
}
function onThirdRequestFinished(/*necessary parameters*/)
{
    monitor.setRequestStatus("thirdRequest", true);
    checkCompleted();
}
function checkCompleted()
{
    if(monitor.allRequestsAreCompleted())
    {
        //Do what you need after all requests are completed
        alert("All requests are completed");
    }
}
onFirstRequestFinished();
onThirdRequestFinished();
onSecondRequestFinished();
</script>