For 10 points, name this programming language often used in webpages.
This language's arguments dot callee gives extra power to anonymous functions. Like Python, it has a for in construction. Commonly used libraries for this language includes Ext, YUI, and Dojo. Primitive types in this language include undefined and null. Instead of using classes, this language like its Self predecessor uses prototypes. Local variables can be declared by the keyword var. For 10 points, name this programming language often used in webpages.
This language's arguments dot callee gives extra power to anonymous functions.
{JavaScript} [or {ECMAScript}; or {JScript}]