K-O-N-A-M-I code!! Key Sequence Detection

KONAMI key sequence code screenshot

KONAMI key sequence code screenshot

For any kid that grew up playing computer games in the 80s and 90s the Konami key sequence brings back fond memories. In the latest tutorial from Wes Bos’ #JavaScript30 course he walks you through how to build this into your web page but instead of extra lives or invincibility you get rainbows and unicorns.

First up an empty array is created and your secret (or Konami) code is assigned to a constant. Then an event listener is added to the window to listen for any time a key on the keyboard is released. Every keystoke is then pushed to the end of the “pressed” array.

The .splice method is then used on the array. We want to match the six characters of the secret code which means keeping the array at a length of six characters. To ensure that key stokes keep passing through the array and not just stop when the array is full at 6 positions we pass as an argument:

-secretCode.length - 1, pressed.length - secretCode.length

This is constantly compared as a string in a if statement to the “secretCode” constant. On a successful key sequence match a rainbow or unicorn is added to the window with the “cornify_add” function.

Phew! What a fun little program. I can’t wait to add this to one of my websites.

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