如何在 javascript 中检测用户是否在滚动?
this works:
window.onscroll = function (e) { // called when the window is scrolled. }
edit:
you said this is a function in a TimeInterval.. Try doing it like so:
userHasScrolled = false; window.onscroll = function (e) { userHasScrolled = true; }
then inside your Interval insert this:
if(userHasScrolled) { //do your code here userHasScrolled = false; }
You just said javascript in your tags, so @Wampie Driessen post could helps you.
I want also to contribute, so you can use the following when using jQuery if you need it.
//Firefox $('#elem').bind('DOMMouseScroll', function(e){ if(e.detail > 0) { //scroll down console.log('Down'); }else { //scroll up console.log('Up'); } //prevent page fom scrolling return false; }); //IE, Opera, Safari $('#elem').bind('mousewheel', function(e){ if(e.wheelDelta< 0) { //scroll down console.log('Down'); }else { //scroll up console.log('Up'); } //prevent page fom scrolling return false; });
Another example:
$(function(){ var _top = $(window).scrollTop(); var _direction; $(window).scroll(function(){ var _cur_top = $(window).scrollTop(); if(_top < _cur_top) { _direction = 'down'; } else { _direction = 'up'; } _top = _cur_top; console.log(_direction); }); });
window.addEventListener("scroll",function(){ window.lastScrollTime = new Date().getTime() }); function is_scrolling() { return window.lastScrollTime && new Date().getTime() < window.lastScrollTime + 500 }
Change the 500 to the number of milliseconds after the last scroll event at which you consider the user to be "no longer scrolling".
(addEventListener is better than onScroll because the former can coexist nicely with any other code that uses onScroll.)
addEventListener
onScroll
You can setup an interval to keep checking if the user has scrolled then do something accordingly.
Borrowing from the great John Resig in his article.
Example:
let didScroll = false; window.onscroll = () => didScroll = true; setInterval(() => { if ( didScroll ) { didScroll = false; console.log('Someone scrolled me!') } }, 250);
See live example
If you want detect when user scroll over certain div, you can do something like this:
window.onscroll = function() { var distanceScrolled = document.documentElement.scrollTop; console.log('Scrolled: ' + distanceScrolled); }
For example, if your div appear after scroll until the position 112:
window.onscroll = function() { var distanceScrolled = document.documentElement.scrollTop; if (distanceScrolled > 112) { do something... } }
But as you can see you don't need a div, just the offset distance you want something to happen.
their are 2 events for that
const elm = document.querySelector("urElement"); elm.onscroll = () => // ... elm.onwheel = () => // ...
I perfer to use onwheel since it gives you more infos like the direction they're scrolling with the wheelDeltaY/wheelDeltaX property and the speed with also wheelDeltaY/wheelDeltaX