$ sudo apt-get update
$ sudo apt-get install libjs-mochikit 

libjs-mochikit is installed in your system.

Make ensure the libjs-mochikit package were installed using the commands given below,

$ sudo dpkg-query -l | grep libjs-mochikit *

You will get with libjs-mochikit package name, version, architecture and description in a table

libjs-mochikit package basic information: