将Javascript值传递到C＃代码隐藏（扫描）中

Question

I've got a scanner that calls a JavaScript function when it scans a barcode. In this function, I am trying to pass the barcode value into some kind of variable that I can use in my C# code behind. I've tried this:

document.getElementById("hidden").value = data;
alert(document.getElementById("hidden").value);

This gets the barcode value scanned and alerts it. In the code behind, I am looking for something like this:

protected void hidden_ValueChanged(object sender, EventArgs e)
{
//magic wizard man stuff going on
}

This doesn't seem to trigger at all. Any ideas?

(Essentially I want a value to get passed into C# Code Behind so I can do stuff with it)

Answer 1

您最终必须做一个回发，但是如果可以创建一个按钮并从javascript代码中单击它，那可能是一个更简单的解决方案。

Answer 2

Attach that event to hidden field like this

<asp:hiddenfield id="hidden"
              onvaluechanged="hidden_ValueChanged"
              value="" 
              runat="server"/>

MSDN source

Answer 3

In order to achieve this, you can use, Page Method. The other alternate is to use jquery, like this(just a code snippet):

$.ajax({
          type: "POST",
          url: "WebForm.aspx/CodeBehindMethod",
          data: "{<your scanner id>}",
          contentType: "application/json; charset=utf-8",
          dataType: "json",
          async: true,
          cache: false,
success: function (msg) 
        {
                       //any div or label you want to update
                }
              })

And in your code behind:

[WebMethod]
public static string CodeBehindMethod(string Id)
{
   //whatever you want to do with the Id
   return Id;
}