View local html files and websites. You can learn javascript by injecting javascript in pages. You can open javascript saved in a file, so that you don't have to type it every time. You can use included file manager to create new file, open it in text editor of your choice, enter js, save and then load it in webpages using this app.

You can make a folder of files containing javascript. You can use those files to inject javascript in webpages you created or in any website.