Javascript started life (at Netscape) as a lightweight client side interpreted scripting language designed to do a few things (in the Netscape browser) that could not be done in HTML.
While this C style, loosely typed (Duck...) interpreted language was viewed by many 'hard core' programmers with a measure of distain, it has metamorphised (exploded may be a better word) into a full featured easy to use multipurpose tool.
Its broad support, the development of AJAX and the plethora of frameworks (JQuery, YUI, et al) make it ever easier to use - the platform of choice for client side web based programming and (more frequently) server side development as well (Node.js being the most notable example).
In short: we do Javascript.