Compiling/ running Javascript in Notepad++ [beginner question]
Javascript does not need to be compiled, you can put it between <script> and </script> in a file, save it as something.html and open it in your browser.
Java needs to be compiled, but that is something completely different.
Just save the sample code to a file, such as "example.html", and then open that file in a browser.
<html>
<script>
alert("hi");
</script>
</html>
You can also download a console plugin that would allow you to execute java scripts without leaving Notepad++. See this video for reference: