Question

for (var i = 0; i < friends.length; i++) {
    var friend = $("<li>" + friends[i].name + "</li>");
    FB.api( /  + eventId +  /invited/  + friends[i].id,  post , {}, function (response) {
        //friend here is the last one created for all callbacks
    });
}

我有一个循环,邀请朋友参加一个活动, 我发现在这里创建的jquery < code> friend 对象总是最后一个为所有回调创建的对象。我假设这是因为Facebook的呼叫是无同步的。我怎样才能在这里保持范围?

Answer 1

尝试此 :

for (var i = 0; i < friends.length; i++) {
    var friend = $("<li>" + friends[i].name + "</li>");
    var callback = (function(friend){
       return function (response) {
          //friend here should be the correct one
       })(friend);
    }
    FB.api( /  + eventId +  /invited/  + friends[i].id,  post , {}, callback);
}

Answer 2

您可以为本地变量创建关闭 :

for (var i = 0; i < friends.length; i++) {
  var friend = $("<li>" + friends[i].name + "</li>");

  (function(friend){

    FB.api( /  + eventId +  /invited/  + friends[i].id,  post , {}, function (response) {
      //friend here is the parameter in the closure, so it s preserved for each item
    });

  })(friend);

}

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