So I am trying to use the JavaScript on scroll to call a function. But I wanted to know if I could detect the direction of the the scroll without using jQuery. If not then are there any workarounds?
I was thinking of just putting a 'to top' button but would like to avoid that if I could.
I have now just tried using this code but it didn't work:
if document.body.scrollTop <= 0 {
alert ("scrolling down")
} else {
alert ("scrolling up")
}
It can be detected by storing the previous scrollTop value and comparing the current scrollTop value with it.
JavaScript :
var lastScrollTop = 0;
// element should be replaced with the actual target element on which you have applied scroll, use window in case of no target element.
element.addEventListener("scroll", function(){ // or window.addEventListener("scroll"....
var st = window.pageYOffset || document.documentElement.scrollTop; // Credits: "https://github.com/qeremy/so/blob/master/so.dom.js#L426"
if (st > lastScrollTop){
// downscroll code
} else {
// upscroll code
}
lastScrollTop = st <= 0 ? 0 : st; // For Mobile or negative scrolling
}, false);
Simple way to catch all scroll events (touch and wheel)
window.onscroll = function(e) {
// print "false" if direction is down and "true" if up
console.log(this.oldScroll > this.scrollY);
this.oldScroll = this.scrollY;
}
Use this to find the scroll direction. This is only to find the direction of the Vertical Scroll. Supports all cross browsers.
var scrollableElement = document.body; //document.getElementById('scrollableElement');
scrollableElement.addEventListener('wheel', checkScrollDirection);
function checkScrollDirection(event) {
if (checkScrollDirectionIsUp(event)) {
console.log('UP');
} else {
console.log('Down');
}
}
function checkScrollDirectionIsUp(event) {
if (event.wheelDelta) {
return event.wheelDelta > 0;
}
return event.deltaY < 0;
}