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

libjs-strophe is installed in your system.

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

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

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

libjs-strophe package basic information: