等待异步结果 [英] Waiting for asynchronous result

问题描述

我生病了以下问题：

我使用Facebook的功能查询一些权限的Facebook的API FB.api（）。我想等这个结果之前，我去上进行一些测试，等我的目标是创建一个小的辅助类此类调用常用的功能：

I query the Facebooks API for some permissions by using the facebook function FB.api(). I want to wait for the result of this before I go on to proceed some tests etc. My aim is to create a small helper class to call often used functions by this class:

var fbHelper = {

    hasPermission: function(permission) {

            var hasPermission = false;
            var requestedPermissions = false;
            var permissions = { };

            FB.api('/me/permissions', function(response){    

                permissions = response;
                requestedPermissions = true;
                return response;
            });

            if(permissions){
                // make some checking stuff here
                return hasPermission;
            } else {
                console.log('failed to /me/permissions');
                return false;
            }        
     }
}

所以我想用 fbHelper.hasPermission（'假'）。不幸的是，如果（权限）之前工作FB.Api（）完成。
如何能够做到等待我的code的其余部分，直到API的调用完成??

So i want to use fbHelper.hasPermission('dummy'). Unfortunately the if(permissions) is worked before FB.Api() is completed. How can I achieve to wait for the rest of my code until the Api-Call is completed??

推荐答案

您真的不能编写一个执行一个异步请求的函数，并期望能够可靠地返回结果。我会调整你的helper方法如下：

You can't really write a function that executes an asynchronous request and expect to be able to reliably return the result. I would restructure your helper method as follows:

hasPermission: function(permission, callback) {

        var hasPermission = false;
        var requestedPermissions = false;
        var permissions = { };

        FB.api('/me/permissions', function(response){    

            permissions = response;
            requestedPermissions = true;
            if (permissions) {
                callback(permissions);
            } else {
                callback(false);
            }
        });     
 }

让调用code供应一个回调函数来执行当Ajax调用已完成。

Let calling code supply a callback function to be executed when the AJAX call has completed.

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