$ sudo apt-get update
$ sudo apt-get install plasma-scriptengine-javascript

plasma-scriptengine-javascript is installed in your system.

Make ensure the plasma-scriptengine-javascript package were installed using the commands given below,

$ sudo dpkg-query -l | grep plasma-scriptengine-javascript*

You will get with plasma-scriptengine-javascript package name, version, architecture and description in a table

plasma-scriptengine-javascript package basic information: