Java script is a prototype-based scripting language with dynamic typing and has first class functions. Its syntax was influenced by C. Java Script copies many names and naming conventions from Java, but the two languages are otherwise unrelated have have very different semantics. The key design principles within Java script are taken from the self and scheme programming language. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles.

The application of Java script to use outside of webs - for example in PDF documents, site-specific browsers, and desktop widgets - is also significant. Newer and faster Java script VMs and platforms built upon them (notably Node js) have also increased the popularity of Java script for server-side web applications. On the client side, Java script was traditionally implemented as an interpreted language but just-in-time compilation is now performed by recent (post-2012) browsers.

Java script was formalized in the ECMA script language standard and is primarily used as a part of a web browser (client-side Java script). This enables programmatic access to computational objects within a host environment.