This document is an introduction to the JavaScript Programming Language for professional programmers. It is a small language, so if you are familiar with other languages, then this won't be too demanding.
JavaScript is not Java. They are two very different languages. JavaScript is not a subset of Java. It is not interpreted Java. (Java is interpreted Java!) JavaScript shares C-family syntax with Java, but at a deeper level it shows greater similarity to the languages Scheme and Self. It is a small language, but it is also a suprisingly powerful and expressive language.You should take a look at it. You will find that it is not a toy language, but a full programming language with many distinctive properties.
P. Buneman, and W. Tan. SIGMOD '07: Proceedings of the 2007 ACM SIGMOD international conference on Management of data, page 1171--1173. New York, NY, USA, ACM, (2007)