asp.net ensure javascript is loaded once only

Question

I've been working in asp.net webforms and I've been making a UserControl that depends on a small bit of javascript which is in an external file. I want to be able to put a reference to the javascript inside the UserControl to ensure that it gets loaded on the page, but the problem is that the UserControl can appear multiple times on a page so I only want the script to be loaded with the first instance of the UserControl. Is there an easy way to do this in ASP.NET Webforms?

Accepted Answer

Use the `ClientScriptManager`'s `RegisterClientScript()` methods to handle this. In your case, since you're including the script from an external file, use `RegisterClientScriptInclude()`.

Alternately, if you're using UpdatePanels, use `ScriptManager`'s equivalent `Register...()` methods.

asp.net ensure javascript is loaded once only

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