Q:

What does it mean $1Z in regular expression

I'm not familiar with regex, but I have the following string
d.$filter = d.$filter.replace(/TutoringSince le '(.+?)'/g, "TutoringSince ge $1Z");

Is anybody know what does it mean this Z char after $1 ? 

A:

It replaces the captured text in the d.$filter, with TutoringSince ge, plus itself then adds a Z. I.e. the text

TutoringSince le 'whatever'

would turn into

TutoringSince ge whateverZ

"The captured text" would be anything inside the single quotes.