Freeze scroll on arrow key up or down using JavaScript
I was working on implementing the Konami code easter egg on this blog and there was this need where I need to stop the scrolling only when the previous two presses by the user are ArrowUp.
To give a primer, the Konami code consists of the following key sequence:
↑↑↓↓←→←→BA
Now, as you can see, the firt two keypresses are ↑↑. I wanted to disable the scrolling on this point onwards. i.e sarting from ↓. Because I wanted the user to be on the same place when he/she presses ↓ after pressing ↑↑.
To check this, I added an event-listener on keydown like so.
document.addEventListener('keydown', function(e) {
// To make sure it freezes the scroll when
// the first two keypresses are "ArrowUp"
if (
keySequence[0] === 'ArrowUp'
&& keySequence[1] === 'ArrowUp'
&& e.key === 'ArrowDown'
) {
e.preventDefault();
}
});
As you can see, I’m checking if the fist two indexes in keySequence(where I store user-entered keystrokes) array contains ArrowUp and the next key is ArrowDown, I would just prevent the scroll by disabling the default key action of ArrowDown using e.preventDefault();.
That’s it! It will disable the scroll further if this scenario happens and that is what I wanted. And the code also makes sure, it behaves like this only if a certain scenario arrives.
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👋 Hi there! I'm Amit. I write articles about all things web development. You can become a sponsor on my blog to help me continue my writing journey and get your brand in front of thousands of eyes.
