Black

Provides functionality missing from the core JavaScript library, for the basic object types.

Stuff added includes things to work with sequences (arrays, and array-likes), sets (objects), strings, numbers, type and interface/duck-type checking and functions.

Licence

Black is licensed under the delicious and permissive MIT licence. you can happily copy, share, modify, sell or whatever — refer to the actual licence text for less information:

$ less LICENCE.txt