pjs is for filtering and transformation like awk/sed/grep, but it supports many different text-based formats and its programs are written in plain JavaScript.

Here's an example that converts a file to uppercase:

    cat file.txt | pjs '_.toUpperCase()'

It can also scrape websites using CSS selectors:

    curl https://aduros.com | pjs --html 'h1,h2' '_.text'

And JSON using jq filters:

    cat database.json | pjs --json '.users[]' '_.age >= 21'

Lots more examples on the README/man page. It's still quite new and may have bugs, if you find one let me know!