无法解析并将ajax字符串返回到jquery变量

问题描述

var data 是我的 jquery 变量，我想在其中添加 jsonData.image_name 字符串文本.但是当它通过时一直说 undefined .

var data is my jquery variable, i want to add jsonData.image_name string text in to it. but keep saying undefined when it passes.

function SaveAndGetImageName() {
    var data = "";
    var formData = new FormData();
    formData.append('btn_Browse', $('#btn_Browse')[0].files[0]);
    $.ajax({
        url: '../Gem/SaveProfilePic',
        type: 'POST',
        dataType: 'json',
        cache: false,
        async: true,
        contentType: false,
        processData: false,
        data: formData,
        success: function (jsonData) {
            data = jsonData.image_name;
        }
    });

    return data;
}

推荐答案

异步调用无法返回数据，需要在成功回调函数中进行操作.由于在数据到达时调用回调，但您在此之前返回数据，因此您将获得 undefined.

you cant return data from Asynchronous calls, you should do the manipulation in the success callback function. As callbacks are called when the data is arrived, but you are returning the data before that so you are getting undefined.

function SaveAndGetImageName(processImageNameCallback) {
    var data = "";
    var formData = new FormData();
    formData.append('btn_Browse', $('#btn_Browse')[0].files[0]);
    $.ajax({
        url: '../Gem/SaveProfilePic',
        type: 'POST',
        dataType: 'json',
        cache: false,
        async: true,
        contentType: false,
        processData: false,
        data: formData,
        success: function (jsonData) {
            data = jsonData.image_name;
            processImageNameCallback(data);
        }
    });

    return data;
}

function processImageName(imageName){
   // do stuff with image name
   alert(imageName);
}

SaveAndGetImageName(processImageName)

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