I'm not a PHP guy and I like to use standards for the languages I'm using so this php.js thing is not for me at all. In fact, I really dislike PHP and though I use it often, there is no reason in the world I would want to use its syntax to write javascript.

Import the librairie (packed) and write javascript like you never wrote it before.

Example, you want to use the good ol' strrpos to find position of last occurrence of a char in a string (example from the site)

strrpos('Kevin van Zonneveld', 'e');
would return 16.

But what happens if a non-PHP guy as to modify your PHPed javascript?