Binding arrow keys in JS/jQuery

Modern key mapping and cross-browser compatibility

Ensuring a compatibility for diverse browsers and an efficient event handling model is crucial. Using event.key property backed by a switch or if statement delivers a cleaner, modern approach:

document.addEventListener('keydown', (event) => {
    let key = event.key || event.keyCode; // Backwards compatibility, like denim jackets!
    switch(key) {
        case 'ArrowLeft': 
        case 37:
            performMagic('left'); 
            event.preventDefault();
            break;
        case 'ArrowUp': 
        case 38:
            performMagic('up'); 
            event.preventDefault();
            break;
        case 'ArrowRight': 
        case 39:
            performMagic('right'); 
            event.preventDefault();
            break;
        case 'ArrowDown': 
        case 40:
            performMagic('down'); 
            event.preventDefault();
            break;
    }
});


Here event.preventDefault() prevents the default action of the arrow keys, like scrolling a webpage, an event equivalent of saying "hold my beer". The event = event || window.event statement ensures compatibility with older versions of Internet Explorer.

Handling multiple keys and efficient events

Handling simultaneous keys

Some users may press multiple keys together to perform composite actions. Imagine a gamer pressing up and right together to move the character diagonally. Here's how you can handle it:

let keys = {};
document.addEventListener('keydown', (event) => {
    keys[event.key] = true;
    combineKeys();
    event.preventDefault(); // Wizards don't let keys roam free!
});
document.addEventListener('keyup', (event) => {
    delete keys[event.key];
});

function combineKeys() {
    if(keys['ArrowUp'] && keys['ArrowRight']) {
        moveDiagonal('up-right'); // Diagonal powers, activate!
    }
    // Add other combinations as desired
}


Optimized event handling

And remember, with great keys comes great responsibility. If dealing with rapid key presses, consider debouncing or throttling the handling function to prevent performance misfires:

document.addEventListener('keydown', throttle((event) => {
    // handle that rowdy event
}, 100)); // Limit execution to once every 100ms, like a good cup of coffee!


Testing for conflicts

Make sure to check for conflicts if attaching key events to multiple elements or when other libraries might have a say in the event. Test your code across browsers and devices, because it's no fun if someone feels left out.

Simpler jQuery key binding

For projects with jQuery, use $(document).keydown() for cleaner syntax and easier readability:

$(document).keydown(function (event) {
    switch(event.which) {
        case 37: move('left'); break;
        case 38: move('up'); break;
        case 39: move('right'); break;
        case 40: move('down'); break;
        default: break; // ignore everything else, like your ex's texts
    }
});


Though js-hotkey plugin exists, remember native solutions are like home-cooked meals - simple and effective.

Advanced key considerations

Keyup event for continuous movement

For continuous character movement, consider the keyup event. When the keys quit, the movement quits, like a Newton's law for JavaScript!

document.addEventListener('keyup', (event) => {
    // Stop movement when the key calls it a day
});


Accessibility and alternatives

Don't forget about accessibility, some users rely on assistive technology or lack arrow keys. Providing alternative navigation modes, such as on-screen buttons, is a sure way to brighten up their day!