Javascript 将值从服务器传递到客户端不起作用

Question

我有一个文件上传控件和一个按钮 webform.When 我在选择文件上传后单击按钮，它应该保存图像并用 GUID 重命名它。

protected void btnUpload_Click(object sender, EventArgs e)
{
    string fileName = string.Empty;
    string filePath = string.Empty;
    string extension = string.Empty;
    try
    {
        //Check if Fileupload control has file in it
        if (FileUpload1.HasFile)
        {
            // Get selected image extension
            extension = Path.GetExtension(FileUpload1.FileName).ToLower();
            //Check image is of valid type or not
            if (extension == ".jpg" || extension == ".jpeg" || extension == ".png" || extension == ".gif" || extension == ".bmp")
            {
                //Cretae unique name for the file
                fileName = Guid.NewGuid().ToString() + extension;
                //Create path for the image to store
                HiddenField1.Value = fileName;
                filePath = Path.Combine(Server.MapPath("~/Images"), fileName);
                //Save image in folder
                FileUpload1.SaveAs(filePath);
                //Show the panel and load the uploaded image in image control.
                //pnlCrop.Visible = true;
        }

上面的代码工作正常，保存图像并将 GUID 传递给 hiddenfield.Now 我想将 hiddenfield 的值传递给客户端变量，然后将其显示为警报。

  <script type="text/javascript">
    function showfilename() {       
        setTimeout(function () {
            var dpGUID = document.getElementById('<%= HiddenField1.ClientID %>').value;
            alert(dpGUID);
        },3000)
    }
</script>

使用超时的原因？因为我想在单击按钮时为它分配值后读取 hiddenfield 的值。

注意：我在 Buttonclick.One 客户端和服务器端使用两个函数，如下所示：

 <asp:Button ID="btnUpload" runat="server" OnClick="btnUpload_Click" Text="Button" OnClientClick="showfilename()" />

可能吗？如果是，可能是什么导致了问题？

Answer 1

尝试使用 RegisterClientScriptBlock

protected void btnUpload_Click(object sender, EventArgs e)
{
    /*All your code here*/
    //instead of HiddenField1.Value = fileName; write the line below
    ScriptManager.RegisterClientScriptBlock(this, typeof(Page), "callJsFunction", "alert('" + fileName + "');", true);
}

现在您可以去掉 OnClientClick="showfilename() 和 HiddenField

Javascript 将值从服务器传递到客户端不起作用

Javascript to pass value from server to client doesnt work

javascript

asp.net

hidden-field