[aniketpant]

I don't get the point why should I use Python to run Javascript.

JS has been in use around the web for a long time now and I don't see the need why should I go about using Python for the very same? Doesn't one language has a purpose of it's own?

If it wasn't the case, then people would have worked on creating a unified language for all our needs.

[icebraining]

Nobody says you should, it's purely a personal preference :)

Doesn't one language has a purpose of it's own?

Usually no, most domains are served by more than one language, otherwise we would all be using Perl to write server-side web applications.

While it's debatable whether JavaScript is particularly well suited for client-side web code, the fact is that having only one language of choice is mostly an historical accident.