README.md

1- JavaScript Drum Kit

Use of <kbd> HTML tag.
What are keycodes & how to use them.
data-* attributes where * can be anything specified. They are like to store custom data on HTML itself
Use of rem for making some responsive & easier working in CSS. I knew but started using now.
Use of attributes in giving class property in querySelector

Whenever we play to play sound then we add playing class in HTML code then the transition effect happened there.
After the transition is done we remove by transionend property.
We use keydown event not keyup event as when the user want to press multiple times then it will not work as stated.
We can play audio in JavaScript by just using .play().
We use window in JavaScript to capture key that are preseed not document.
audio.currentTime = 0 for rewinding sound. Use to prevent delaying sound. this is pretty important.