如何在for循环中返回数组作为promise？ [英] How to return array in for loop as promise?

问题描述

我试图将数组作为可以在函数中调用的promise返回。但它会在调用完成之前返回。请帮帮我怎么办呢？



我尝试过：

I am trying to return the array as a promise which can be called in a function. But it returns before the call completes. Please help me how can I do that?

What I have tried:

function getNewAddedSchedules() {
    var newScheduleArray = [];
    return localforage.getItem("schedulesOffline")
        .then(function (value) {
            for (var i = 0; i < value.length; i++) {
                 ScheduleApi.schedule("57cd27fa390feec82e3be851")
                    .then(function (data) {
                        if (data === "") {
                            newScheduleArray.push(value[i]);
                        }
                    });
            }
            return newScheduleArray;
        });
};


function saveOfflineToOnline() {
    getNewAddedSchedules().then(function (data) {
        console.log(data);
    });
}

推荐答案

您正在尝试在循环中进行多个异步调用。但是你要返回一个承诺，这会导致这个问题。相反，您可以使用

Hi,

You are trying to make multiple async calls within a loop. But you are returning a single promise, which is causing this issue. Instead, you can utilize

q.all来解决此问题。这是一个例子 -



JS Bin - Collaborative JavaScript调试 [ ^ ]



注意aysnc调用函数如何返回一个promise和处理函数应该将它推送到promise数组中。



如果您有任何问题，请告诉我。



谢谢。

q.all to resolve this issue. Here's an example -

JS Bin - Collaborative JavaScript Debugging[^]

Notice how aysnc call function should return a promise and handling function should push it in a promise array.

Let me know if you any questions.

Thanks.

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