我无法在 JavaScript 中获取数组长度

Question

我有 JavaScript 数组并从 mvc modal 填充数据：

<script type="text/javascript">
    var letterOfResponsibilityNotes = Array(0);

    @if (Model.Step2.SelectedCountryList.Count != 0)
    {
        foreach (var item in Model.Step2.SelectedCountryList)
        {
            <text>letterOfResponsibilityNotes["@item.Code"]='@item.LetterOfResponsibilityNote'</text>
        }
    } 

然后我尝试获取letterOfResponsibilityNotes数组长度：

if ($(letterOfResponsibilityNotes).length > 0)
{ ... }

但我总是得到lenth = 0，尽管我在 FireBug 中看到了数据。

谢谢！

Answer 1

那是因为@item.Code 不是数字。

var a = new Array(0);
a["test1"] = "test1";
a["test2"] = "test2";

// a.length is still 0 - although it has contents

a["3"] = "try a number";

// now a.length == 4, which is highest number subscript key + 1
// unfortunately that is how JS arrays work

要查找数组的长度，请参阅Length of a javascript associative array

Answer 2

试试这个：

first initialize the as follow in JavaScript.

var letterOfResponsibilityNotes = new Array();

console.log(letterOfResponsibilityNotes.length);

if(letterOfResponsibilityNotes.length > 0)
{

}

if array have any value it display length of array.

Answer 3

在 IF 上删除“$”。

if ((letterOfResponsibilityNotes).length > 0)
{ ... }

用 $ 我失败了

未捕获的引用错误：$ 未定义