Language Details: Javascript

JavaScript is a prototype-based scripting language that is dynamic, weakly typed, and has first-class functions.

JavaScript article on Wikipedia
Code Jam 2009 Contestants using Javascript
Qualification Round
Used in 68 solutions by 21 contestants:
Round 1A
Used in 4 solutions by 4 contestants:
Round 1B
Used in 4 solutions by 3 contestants:
Round 1C
Used in 7 solutions by 7 contestants:

Submission Origin

United States (6 contestants)
Japan (4 contestants)
China (3 contestants)
Spain (2 contestants)
Argentina (1 contestant)
Australia (1 contestant)
Brazil (1 contestant)
India (1 contestant)
Italy (1 contestant)
Latvia (1 contestant)
Thailand (1 contestant)
Turkey (1 contestant)
United Kingdom (1 contestant)