Programmatically adding Javascript File to User Control in .net

You can register client script includes using the ClientScriptManager. Page is accessible through the Control.Page property.

Page.ClientScript.RegisterClientScriptInclude (
  typeof ( MyControl ), "includeme.js", "js/includeme.js"  );

EDIT: Sorry, for a total "complete package", its possible using scripts as Embedded Resources, and aquire dynamic URL's through the WebResource.axd handler. If this is not considered totally complete, then i guess it could be put in App_LocalResources, but it never gonna be just one file, unless the code and script is inline.

Good question!

A UserControl should be a single package without any dependency on a JavaScript or a CSS file. You will need to make the JS and CSS files as embedded resources. Right click properties and set build action to embedded resources. Then you need to inject the JavaScript and CSS files as WebResources.

Here is one article that I wrote yesterday which talks about the same scenario:

http://highoncoding.com/Articles/502_Creating_RadioButton_Validation_Using_Custom_Validator.aspx

In my site I Place all needed scripts and styles to placeHolder

<asp:placeHolder runat="Server" ID="phHead">
    <script src="/header/widget/script.js" type="text/javascript"></script>
    <link href="/header/widget/style.css" rel="stylesheet" type="text/css" />
</asp:placeHolder>

and

Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    Page.Header.Controls.Add(phHead)
End Sub

The same as gnomixa's response, only a bit cleaner:

HtmlGenericControl js = new HtmlGenericControl("script");
js.Attributes["type"] = "text/javascript";
js.Attributes["src"] = "jscript/formfunctions.js";
Page.Header.Controls.Add(js);

from http://www.aspdotnetfaq.com/Faq/How-to-Programmatically-add-JavaScript-File-to-Asp-Net-page.aspx

I generally do it when rendering the HTML for the control and depending on whether it's a library injection or an instance injection I use the Items collection to specify whether or not I have already produced the code for a control of this type during the current request using a unique identifier.

Something to the effect of:

    protected override void Render(HtmlTextWriter writer)
	{
		base.Render(writer);

		//Check if the Object Script has already been rendered during this request.
		if (!Context.Items.Contains("xxx"))
		{
			//Specify that the Object Script has been rendered during this request.
			Context.Items.Add("xxx", string.Empty);
			//Write the script to the page via the control
			writer.Write([libraryinjection]);
		}
		//Write the script that instantiates a new instance for this control
		writer.Write([instanceinjection]);
	}

If you have the text of the actual javascript in your .CS file, you can call Page.ClientScript.RegisterClientScriptBlock.

The following assumes that "GetScript()" returns the actual javascript you want added to the rendered control.

Page.ClientScript.RegisterClientScriptBlock(GetType(), "controlScriptName", GetScript());

I found this to be a more elegant way to fix-link to your javascript.
In your .ascx, link to your script files the following way:

<script src='<%= ResolveClientUrl("~/Scripts/jquery-1.7.1.min.js") %>' type="text/javascript"></script>
<script src='<%= ResolveClientUrl("~/Scripts/jquery.maskedinput-1.3.min.js") %>' type="text/javascript"></script>

That way, no matter which subfolder/page you add your user control to, the link to your scripts will always be correctly resolved.