如何添加javascript代码到LinkButton通过服务器代码c#

我正在创建一个带有链接按钮的可视化web部件，链接按钮应该打开一个模态弹出窗口。

我已经定义了函数，但我不确定如何使链接按钮触发javascript函数。

请参阅CreateChildControls方法

    <asp:Content ID="Content1" ContentPlaceHolderId="PlaceHolderAdditionalPageHead" runat="server">
        <script type="text/javascript">
            function dialogfunction(pageUrl) {
                var options = { url: pageUrl, width: 900, height: 300 };
                SP.SOD.execute('sp.ui.dialog.js', 'SP.UI.ModalDialog.showModalDialog', options);
            }
        </script>
    </asp:Content>
    <asp:LinkButton ID="LnkButton" runat="server"></asp:LinkButton>

  public partial class LinkButton : WebPart
    {
        // Visual Studio might automatically update this path when you change the
        // Visual Web Part project item.
        private const string _ascxPath =@"~/_CONTROLTEMPLATES/VisualWebParts/LinkButton/LinkButton.ascx";
        private string _LinkText;
        private Uri _Link;

        [WebBrowsable(true), WebDisplayName("LinkText"), WebDescription("Text for the link"),
        Personalizable(PersonalizationScope.Shared), Category("xx- xx"),
        System.ComponentModel.DefaultValue("")]
        public string LinkText
        {
            get { return _LinkText; }
            set { _LinkText = value; }
        }
        [WebBrowsable(true), WebDisplayName("Link"), WebDescription("Link"),
        Personalizable(PersonalizationScope.Shared), Category("xx- xx"),
        System.ComponentModel.DefaultValue("")]
        public Uri Link
        {
            get { return _Link; }
            set { _Link = value; }
        }
        // Uncomment the following SecurityPermission attribute only when doing Performance Profiling on a farm solution
        // using the Instrumentation method, and then remove the SecurityPermission attribute when the code is ready
        // for production. Because the SecurityPermission attribute bypasses the security check for callers of
        // your constructor, it's not recommended for production purposes.
        // [System.Security.Permissions.SecurityPermission(System.Security.Permissions.SecurityAction.Assert, UnmanagedCode = true)]
        public LinkButton()
        {
        }
        protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);
            InitializeControl();
        }
        protected void Page_Load(object sender, EventArgs e)
        {
        }
        protected override void CreateChildControls()
        {
            LinkButton linkButton = Page.LoadControl(_ascxPath) as LinkButton;
            if (linkButton != null)
            {
                linkButton.Title = LinkText;
                linkButton.TitleUrl = Link.ToString();
                Controls.Add(linkButton);
            }           
        }
    }

linkButton.Attributes.Add("onclick", "dialogfunction('" + Link.ToString() + "');");

protected override void CreateChildControls()
        {
            LinkButton linkButton = Page.LoadControl(_ascxPath) as LinkButton;
            if (linkButton != null)
            {
                linkButton.Title = LinkText;
                linkButton.TitleUrl = Link.ToString();
                /*************************************************************/
                /* you can replace "alert('test');" with any javascript
                i.e a function call */
                linkButton..Attributes.Add("onclick", "alert('test'); ");
                /*************************************************************/
                Controls.Add(linkButton);
            }           
        }

public string LinkOnClientClick
{
    get; set;
}
protected override void CreateChildControls()
{
   LinkButton linkButton = Page.LoadControl(_ascxPath) as LinkButton;
   if (linkButton != null)
   {
         linkButton.Title = LinkText;
         linkButton.TitleUrl = Link.ToString();
         linkButton.OnClientClick = LinkOnClientClick;
         Controls.Add(linkButton);
   }           
}