We can't go in alone.

We can't go in alone.

The MDN is your exit buddy.

Ok developers! You have your basic gear .

But we're still on the beach. We need a friend to go in with us.


The MDN, or Mozilla Developer Network , is your exit buddy. After some training, you'll be able to refer to it to help you out of a tight spot.

But.... HOW? What do I actually DO with the MDN? How do I get to know it?

Take the MDN on an Active Recall date.


< remember anything forever-ish >

To prepare, spend a few minutes with each of the most common string and array methods.

You've just met, and you'll need to meet regularly in order to get to know each other well.

Don't panic, and don't stress about memorization. You're just making a friend.

On each card, write down what the method takes in, what it does, and what it returns.

If handwriting on index cards isn't your style, ANKI is a handy, free online tool. But if you use it, remember to actually type out your cards. You are not saving time, you are just making your future swim more difficult.

Start Here:

15 Common String Methods:

charCode At concat includes indexOf
match repeat replace search slice
split substr toLowerCase toUpperCase Trim

13 Common Array Methods:

Map Reduce Filter forEach sort
slice pop shift push unshift
includes indexOf every


With your exit buddy there to assist, we'll soon get our feet wet using some of the string methods to solve our very first Codewars challenges!