Question

我有以下代码块

var cars = $('#mypage').data('carsdata');

if (cars == null) {
    var clientId = $("input[name='ClientId']").val();
    worksheet.ajax.execute('GET','/Cars/GetData/', { clientId: clientId }, function (res) {
        if (res == "") {
            return;
        }

        cars = res.Owners.filter(function (e) {
            if (e.Email) {                        
                return true;
            }
            return false;
        }).map(function (e) {                
            return { key: e.Id, label: e.Email };
        });

        console.log("1" +cars.length); // cars lenght is 3
 });


console.log("2" +cars.length); // cars is null

也许这是太多的代码，但问题是最后一行的汽车变量总是为空，即使我有if语句，我检查null，在那种情况下，我填充该变量，在

console.log("1" +cars.length);

汽车长度是3，所以它不是空的。为什么这个cars.length没有在

上复制

console.log("2" +cars.length);

这个map function是否可以正常填充汽车变量？

更新

当汽车正确加载数据属性时，我会以下列格式获取数据

[Object {key = 101，label =＆＃34; email@email.com"}，Object {key = 22， label =＆＃34; email2@email.com"}，Object {key = 442，标签=＆＃34; email43@email.com"}]

Answer 1

那是因为你在cars的回调中填充了worksheet.ajax.execute( )

异步调用，因此您的应用程序流量与预期不同，请遵循以下顺序：

var cars = $('#mypage').data('carsdata');
//1) cars is null here

if (cars == null) {
    //...        
    //2) get inside the if statement and start the ajax call
    //   cars is null here
    worksheet.ajax.execute('GET','/Cars/GetData/', { clientId: clientId },
        function (res) {
            //...
            //4) the ajax call return his value, and cars is updated
            cars = res.Owners.filter( ... )

            //5) now cars has the correct value
            console.log("1" +cars.length); // cars lenght is 3
        })
}

//3) get out of the if statement, print the console log 
//   cars is still null here
console.log("2" +cars.length); // cars is null

map函数而不是填充变量

1 个答案: