如何循环通过我/朋友，并从FB.api的{USERID} /图片分配每个用户的图片 [英] How to loop through me/friends and assign each user it's picture from {USERID}/picture from FB.api

问题描述

使用javascript我得到Facebook的朋友的列表，虽然它只返回名称和id现在，但我需要获取每个用户的图片。我尝试循环响应，然后尝试调用api来获取图片，但是由于它是异步调用，我无法将返回的图片与数组中的朋友的索引相关联。 *这是一个与异步编程一般的问题，是否有一个标准模式？

Using javascript I get list of facebook friends though it only returns name and id now, but I need to get the picture of each user. I try to loop through the response and then try to call the api to get picture, but due to it's async call I can't associate the returned picture with the index of the friend in the array. *this is kinda a problem that I've had with asynchronous programming in general, is there a standard pattern for this?

示例。

FB.api('me/friends', function(response) {
    if(response.error == null){
        var friendsSale = response.data;
        var len = friendsSale.length;
        for(var x=0; x<len; x++){               
                FB.api(friendsSale[x].id+'/picture', function(response) {
                    //x no longer is the same x as the initial call, and I can't pass in the orignal array object into the FB.api function to return as part of the response... or can I?
                    friendsSale[x].pictureUrl = response;
                });
            }
        }
        //Then how do I know when I have all the pictures set so I can then set datamodle with the complete friend array?
        m.friends(friendsSale);
    }
});

推荐答案

是的，有一个模式： a href =https://developer.mozilla.org/en/JavaScript/Guide/Closures =nofollow>关闭

Yes, there is a pattern for this: a Closure

    ...
    var len = friendsSale.length;
    for (var i = 0; i < len; i++) {
        (function() {
            var j = i;             
            FB.api(friendsSale[i].id+'/picture', function(response) {
                friendsSale[j].pictureUrl = response;
            });
        })();
    }

要知道所有的所有呼叫都已经返回，您可以简单地保留返回的计数器电话，例如

To know when all all calls have returned you can simply keep a counter of returned calls, e.g.

    ...
    var len = friendsSale.length;
    var returnedCallsCounter = 0;

    for (var i = 0; i < len; i++) {
        (function() {
            var j = i;             
            FB.api(friendsSale[i].id+'/picture', function(response) {
                friendsSale[j].pictureUrl = response;

                // Track number of returned calls
                returnedCallsCounter++;

                // Check if all calls have returned
                if (returnedCallsCounter == len) {
                    m.friends(friendsSale);
                }
            });
        })();
    }

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