Finding a div in my SharePoint 2010 Web Part

I have a Web Part that dynamically inserts div tags written in VS2010 using C#. I want to implement mouseover events for these div's. When the Web Part 开发者_如何转开发is deployed onto SP2010, my JavaScript is not able to find these div's when I just search for them with the control id that I have specified.

When I checked the page source, I found that some tags like ct100_m_g_ are prefixed to the control id that I have specified.

How can I guess these ids?

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The ctlxxx stuff is automatically prepended to the control's ID by ASP.NET, to generate the client ID.

If you want to set a deterministic client ID, you can set the ClientID property instead of the ID property. See http://msdn.microsoft.com/en-us/library/system.web.ui.control.clientid.aspx

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In webparts you can use the client ID to find your controls in javascript. Take a look at this example and it will become clear:

using System;
using System.Text;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

namespace MyDemo.WebParts
{
    public class MyWebPart : WebPart
    {
        private TextBox txtInput;
        private TextBox txtOutput;
        private Button btnDoSomething;

        protected override void CreateChildControls()
        {
            base.CreateChildControls();

            txtInput = new TextBox();
            Controls.Add(txtInput);

            txtOutput = new TextBox();
            txtOutput.ReadOnly = true;
            Controls.Add(txtOutput);

            btnDoSomething = new Button();
            btnDoSomething.Text = "Do Something";
            btnDoSomething.OnClientClick = string.Format("DoSomething('{0}', '{1}'); return false;", txtInput.ClientID, txtOutput.ClientID);
            Controls.Add(btnDoSomething);
        }

        protected override void OnPreRender(EventArgs e)
        {
            base.OnPreRender(e);

            // Check if the script is already registered, this is necessary because the webpart can be
            // added multiple times to the same page
            if (!Page.ClientScript.IsClientScriptBlockRegistered("MyWebPartScript"))
            {
                StringBuilder sb = new StringBuilder();
                sb.Append("function DoSomething(inputControlID, outputControlID){");
                sb.Append("  var inputControl = document.getElementById(inputControlID);");
                sb.Append("  var outputControl = document.getElementById(outputControlID);");
                sb.Append("  outputControl.value = inputControl.value;");
                sb.Append("}");

                Page.ClientScript.RegisterClientScriptBlock(GetType(), "MyWebPartScript", sb.ToString(), true);
            }
        }

        protected override void RenderContents(System.Web.UI.HtmlTextWriter writer)
        {
            EnsureChildControls();

            writer.Write("<table>");
            writer.Write("<tr><td>");
            txtInput.RenderControl(writer);
            writer.Write("</td><td>");
            txtOutput.RenderControl(writer);
            writer.Write("</td></tr><tr><td colspan=\"2\">");
            btnDoSomething.RenderControl(writer);
            writer.Write("</td></tr></table>");
        }
    }
}

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You could give each of your DIVs a class when generating them. THen, just use the class name to select them and add the event handler.