There are lots of free web hosting providers who support javascript and HTML files and other promising languages. please check one of them. like GoogieHost

If you are using PHP for creating a website, it will turn into a mess if you don't use separate files for CSS & Javascript. It is not that much of a problem as external javascript functions are not that difficult to call from html or php files. The code looks neat and we can differentiate the problem areas more accurately.

The problem obviously resides when you use ASP.NET & call external javascript files. ASP.NET assigns different client side and server side ids for controls. It maybe a good idea there to discard the external coding of javascript if javascript functions are not called

You can save JavaScript files with any text editor of your liking. Just add the .js file extension and you're good to go.

The suffix for React components is typically .jsx for JSX files and .js for JavaScript files. However, some developers may use .tsx for TypeScript files when using TypeScript with React.

JavaScript files can be created with the extension .js

Note that an accompanying HTML file must reference it in order for it to run as JavaScript. You can include the file in your HTML document by adding the following to the head or body of the document:

<script type="text/javascript" src="myJavaScriptFile.js"></script>

Replace myJavaScriptFile.js with the file name of your JavaScript file.