JavaScriptBuilder: JavaScript Handler Class for Custom Controls

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;
using CP.WebControls;

[assembly: TagPrefix("CP.WebControls", "cpccnt")]

namespace CP.WebControls
{
	/// <summary>
	/// Summary description for ClickCounter.
	/// </summary>
	[
	DefaultProperty("StartValue"), 
	ToolboxData("<{0}:ClickCounter runat=server></{0}:ClickCounter>")
	]
	public class ClickCounter : System.Web.UI.WebControls.WebControl
	{
		/// <summary>
		/// The initial value of the counter
		/// </summary>
		[
		Bindable(true), 
		Category("Appearance"), 
		DefaultValue(0),
		Description("The initial value of the counter")
		] 
		public int StartValue
		{
			get
			{
				if (! (ViewState["StartValue"] is int))
					ViewState["StartValue"] = 0;
				return (int) ViewState["StartValue"];
			}

			set
			{
				ViewState["StartValue"] = value;
			}
		}

		/// <summary>
		/// Prefix text
		/// </summary>
		[
		Bindable(true), 
		Category("Appearance"), 
		DefaultValue("Counter:"),
		Description("Prefix Text")
		] 
		public string Text
		{
			get
			{
				if (! (ViewState["Text"] is string))
					ViewState["Text"] = "Counter:";
				return (string) ViewState["Text"];
			}

			set
			{
				ViewState["Text"] = value;
			}
		}

		[
		DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)
		]
		protected virtual string IncrementScriptName
		{
			get
			{
				return "ClickCounter_IncrementValue";
			}
		}

		[
		DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)
		]
		protected virtual string IncrementScript
		{
			get
			{
#if DEBUG
		JavaScriptBuilder jsb = new JavaScriptBuilder(true);
#else
		JavaScriptBuilder jsb = new JavaScriptBuilder();
#endif
		jsb.AddCommentLine("Splits the inner text into Text (txt) and Counter (c) parts,");
		jsb.AddCommentLine("increments (c) and joins them back together again.");
		jsb.AddLine("function ", IncrementScriptName, "(elmt)");

		jsb.OpenBlock(); // function (elmt)
		jsb.AddCommentLine("Initialize variables");
		jsb.AddLine("var inner = elmt.innerText;");
		jsb.AddLine("var c = 0;");
		jsb.AddLine("var txt = \"\";");

		jsb.AddLine();

		jsb.AddCommentLine("Run through inner text string");
		jsb.AddLine("for (idx = 0; idx < inner.length; idx++)");

		jsb.OpenBlock(); // for (idx...)
		jsb.AddCommentLine("Split string into text and counter parts");
		jsb.AddLine("c = parseInt( inner.substring (idx, inner.length + 1) );");
		jsb.AddLine("txt = inner.substring(0, idx);");

		jsb.AddLine();

		jsb.AddCommentLine("If we have a number, get out of the loop");
		jsb.AddLine("if ( ! isNaN( c ) )");

		jsb.OpenBlock(); // if ( ! isNaN( c ) )
		jsb.AddLine("break;");
		jsb.CloseBlock(); // if ( ! isNaN( c ) )
				
		jsb.CloseBlock(); // for (idx...)

		jsb.AddLine();
		jsb.AddCommentLine("Increment counter");
		jsb.AddLine("c++;");
		jsb.AddCommentLine("Rebuild the string and put it in the inner text"); 
		jsb.AddLine("elmt.innerText = txt + \" \" + c;");
		jsb.CloseBlock(); // function (elmt)

		return jsb.ToString();
			}
		}

		/// <summary> 
		/// Render this control to the output parameter specified.
		/// </summary>
		/// <param name="output"> The HTML writer to write out to </param>
		protected override void Render(HtmlTextWriter output)
		{
			if (!Page.IsStartupScriptRegistered(IncrementScriptName))
				Page.RegisterStartupScript(IncrementScriptName, IncrementScript);

			output.AddAttribute(HtmlTextWriterAttribute.Onclick, String.Concat(IncrementScriptName, "(this);"));
			this.RenderBeginTag(output);

			output.Write(Text.Trim());
			output.Write(" ");
			output.Write(StartValue.ToString());

			this.RenderEndTag(output);
		}
	}
}