等待AJAX​​，然后继续执行单独的功能 [英] Wait for AJAX before continuing through separate function

问题描述

好的...凌晨2点，这是我画线的地方.求助...在我的笔记本电脑最终没出窗户之前. :)

Alright... at 2am, this is where I draw the line. Help... before my laptop ends up going out the window. :)

我已经尝试过使用setTimer，回调和我能想到的所有其他功能(当然还有其他一些Stackoverflow提示).我已经剥离了所有内容，所以只剩下基本代码.

I've tried using setTimer, callbacks, and everything else I can think of (along with a few other Stackoverflow hints of course). I've stripped out everything so I'm leaving just the base code.

我想要做的是调用parseRow()，然后在最后保存记录之前，我需要获取关联的Category(通过AJAX)；但是，它吹过去了，因此类别始终是未定义".

What I'm looking to do is call parseRow() and before it saves the record at the end, I need to grab the associated Category (via AJAX); however, it blows right past it so category is always "undefined".

function parseRow(row){
    var rowArray     = row.trim().split(",");
    var date         = rowArray[0];
    var checknum     = rowArray[1];
    var payee        = rowArray[2];
    var memo         = rowArray[3];
    var amount       = rowArray[4];

    //ERROR: blows right past this one and sets the category variable BEFORE ajax returns
    var category = autoSelectCategory(payee);

    saveRecord(date, checkNum, payee, memo, category, payment, deposit);
}

function autoSelectCategory(payee) {
    var data;
    $.ajax({
        async: false,
        url: "autoselectcategory",
        dataType: "json",
        data: {
            string: payee
        },
        success: function (returnedData) {
            data = returnedData;
        }
    });
    return data;
}

推荐答案

AJAX表示异步.这意味着在您的原始代码中，saveRecord将在客户端收到服务器的响应之前执行(并且根据$.ajax的实现，可能在客户端发送之前请求到服务器).

AJAX stands for asynchronous. That means that in your original code, saveRecord will be executed before the client will receive the response from the server (and, depending on the $.ajax implementation, it might be before the client will send the request to the server).

此外，您似乎误解了JS中函数的工作方式. var category = autoSelectCategory(payee);将类别设置为autoSelectCategory的返回值；但是代码中的autoSelectCategory函数什么也不返回.

Additionally, you seem to misunderstand how functions work in JS. var category = autoSelectCategory(payee); will set the category to the return value of autoSelectCategory; but the autoSelectCategory function in your code returns nothing.

另一方面，匿名函数的data返回值只能由$.ajax函数使用($.ajax可能会忽略success参数的返回值).

From the other side, the data return value of your anonymous function could only be used by $.ajax function (and $.ajax likely ignores the success parameter return value).

这是应该起作用的代码:

Here is the code that should work:

function parseRow(row){
    var rowArray     = row.trim().split(",");
    var date         = rowArray[0];
    var checknum     = rowArray[1];
    var payee        = rowArray[2];
    var memo         = rowArray[3];
    var amount       = rowArray[4];

    autoSelectCategory(payee, function (category) {    
        saveRecord(date, checkNum, payee, memo, category, payment, deposit);
    });
}

function autoSelectCategory(payee, callback) {
    $.ajax({
        async: false,
        url: "autoselectcategory",
        dataType: "json",
        data: {
            string: payee
        },
        success: callback
    });
}

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