Smooth vertical scrolling on mouse wheel in vanilla javascript?
I am a huge fan for vanilla javascript, currently I am working on a project where I need to implement smooth scrolling on mouse wheel scroll. I want to implement this using vanilla JS. I found a jQuery snippet on doing some research which go like below.
$(window).on('mousewheel DOMMouseScroll', function(e) {
var dir,
amt = 100;
e.preventDefault();
if(e.type === 'mousewheel') {
dir = e.originalEvent.wheelDelta > 0 ? '-=' : '+=';
}
else {
dir = e.originalEvent.detail < 0 ? '-=' : '+=';
}
$('html, body').stop().animate({
scrollTop: dir + amt
},500, 'linear');
});
Can anyone help me out as in how to implement a smooth scroll without using a helper library like jQuery or any other library.
There are many implementations that people have done in jQuery. But I want a best implementation that one can do in vanilla JS. That can implemented anywhere in React, Angular & Vue anywhere.
Answer
How about this:
function init(){
new SmoothScroll(document,120,12)
}
function SmoothScroll(target, speed, smooth) {
if (target === document)
target = (document.scrollingElement
|| document.documentElement
|| document.body.parentNode
|| document.body) // cross browser support for document scrolling
var moving = false
var pos = target.scrollTop
var frame = target === document.body
&& document.documentElement
? document.documentElement
: target // safari is the new IE
target.addEventListener('mousewheel', scrolled, { passive: false })
target.addEventListener('DOMMouseScroll', scrolled, { passive: false })
function scrolled(e) {
e.preventDefault(); // disable default scrolling
var delta = normalizeWheelDelta(e)
pos += -delta * speed
pos = Math.max(0, Math.min(pos, target.scrollHeight - frame.clientHeight)) // limit scrolling
if (!moving) update()
}
function normalizeWheelDelta(e){
if(e.detail){
if(e.wheelDelta)
return e.wheelDelta/e.detail/40 * (e.detail>0 ? 1 : -1) // Opera
else
return -e.detail/3 // Firefox
}else
return e.wheelDelta/120 // IE,Safari,Chrome
}
function update() {
moving = true
var delta = (pos - target.scrollTop) / smooth
target.scrollTop += delta
if (Math.abs(delta) > 0.5)
requestFrame(update)
else
moving = false
}
var requestFrame = function() { // requestAnimationFrame cross browser
return (
window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(func) {
window.setTimeout(func, 1000 / 50);
}
);
}()
}p{
font-size: 16pt;
margin-bottom: 30%;
}<body onload="init()">
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</body>Use it by calling new SmoothScroll(target,speed,smooth)
Arguments:
- target: the element to be scrolled smoothly - can be a div or
document - speed: the amout of pixels to be scrolled per mousewheel step
- smooth: the smoothness factor, the higher the value, the more smooth.
Thanks to @Phrogz for the mousewheel normalization.
EDIT: Since Chrome 73 it is required to mark the event listener for the mousewheel event as non-passive in order to be able to call preventDefault() on it. Thanks to @Fred K for this.