If you want to code in Java Script you can use multiple apps like:
Sublime Text: It a versatile, powerful, and fast text editor and code editor known for its speed, ease of use, and extensibility, with support for numerous programming and markup languages, search and replace with regular expressions, and a customisable interface.
Eclipse: It is a free, open-source, and extensible Integrated Development Environment (IDE) primarily used for Java development, but also supporting numerous other programming languages through plugins.