‘Higher-order functions’ is a fancy term for functions that take other functions as arguments or that return functions. Very powerful!

JavaScript variables hold a wide variety of information and can be used with virtually any data type. Here's how to use variables to store numbers, text strings, objects, and more.

It's been a while since I worked on regexs in JavaScript, but generally the way you do this in most programming languages is to build the regex as a string and then pass it into the regex engine.