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Rockin Synth

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Last modified on
Rockin Synth
Photo by Maria D. Campbell on Interglobalmedia

🎶 Description

  • When the user presses a key, it creates a sound. Specifically a musical note corresponding to that of a real piano.

  • When the user presses a key, a transition is triggered. When the user presses down on the key, becomes a bit bigger and turns yellow. When the user lifts his/her finger from the key, the key scales down to its regular size and the yellow background disappears.

🎶 The playSound() function

  • The playSound() function creates the sound for the piano key. It also adds a class called .playing which increases the size of the key, adds a yellow background and box-shadow.

  • First I had to check whether there is an audio element on the page that has an audio data-key attribute.

  • Using an audio[data-key] makes the selection more specific instead of simply using a class, For example. storing the e.keyCode (event keycode) as an attribute value of the data-key attribute makes it possible to be even more specific without having to call the .querySelector() method on each unique and individual key.

  • Next I had to select a corresponding kbd[data-key="${e.keyCode}"] so I could add the animation to it. So the audio tag is for the sound, and the corresponding <kbd> (keyboard) tag is for the animation.

🎶 The removeTransition() function

  • First I had to create a condition to determine whether the transform property is present on a key or not:
if (e.propertyName !== 'transform') return

In other words, if there is no .playing class and therefore no transform property attached to a key, return (skip the key).

  • Otherwise, remove the .playing class from the key:
  • this refers to the key. That's because this is always equal to whatever the event listener gets called against, and that's the key (as indicated further down the code).

🎶 Adding event listeners

  • Last of all, I had to add event listeners to listen for the playSound event and the removeTransition event.

  • First I set up the .addEventListener() method that would be on the lookout for the transitionend event type. The removeTransition reference is triggered when the transitionend event occurs, and the .playing class is removed from the piano key.

  • This time I didn't need to be specific about which particular key with a particular keyCode I had to target, so I did the following with the .querySelectorAll() method:

const keys = document.querySelectorAll('kbd')
  • Then I had to add the event listener to each key:
keys.forEach((key) => key.addEventListener('transitionend', removeTransition))
  • By choosing to use different selectors for the key variable in the playSound() function and the global keys variable, the event listener is nice and separate from the querySelectors in the body of the playSound() function. this way, If I wanted to play sound based off of another element, I could.

  • Finally, I called an .addEventListener() method on the window to listen for a keydown event that would trigger the reference to the playSound function. This means that when someone keys down, play a sound.

window.addEventListener('keydown', playSound)

As I no longer have an actual piano to reference for looks, I have to thank LFeh. I used his keyboard as a visual reference. I also wasn't able to find any mp3 notes for the piano sounds, so I have LFeh to thank for that too. To learn more about his project, please visit the piano repo.

This keyboard is meant to be played by pressing down Computer keys. That means on a laptop or desktop, or any other device that has a keyboard hooked up to it.

Project Includes

babel, ekeyCode, ewhich, es6 modules, eslint, event delegation, event listeners, htm5 audio, kbd tags, prettier, transitions, web audio api