How to get a MouseWheel Event to fire only once in jQuery? - javascript

So I want to fire a function only once every time a user scrolls up or down via the Mousewheel. See: jsFiddle Demo. The issue is that even though I have the e.preventDefault(), the function still fires multiple times.
The goal is for the function to fire only once whenever a user scrolls up or down. Similar to this site.
Here is the code that I have so far:
var sq = {};
sq = document;
if (sq.addEventListener) {
sq.addEventListener("mousewheel", MouseWheelHandler(), false);
sq.addEventListener("DOMMouseScroll", MouseWheelHandler(), false);
} else {
sq.attachEvent("onmousewheel", MouseWheelHandler());
}
function MouseWheelHandler() {
return function (e) {
var e = window.event || e;
var delta = Math.max(-1, Math.min(1, (e.wheelDelta || -e.detail)));
if (delta < 0) {
/* Scroll Down */
e.preventDefault();
console.log("Down. I want this to happen only once");
} else {
/* Scroll Up */
console.log("up. I want this to happen only once");
e.preventDefault();
}
return false;
}
return false;
}

This has helped me:
var isMoving=false;
$(document).bind("mousewheel DOMMouseScroll MozMousePixelScroll", function(event, delta) {
event.preventDefault();
if (isMoving) return;
navigateTo();
});
function navigateTo(){
isMoving = true;
setTimeout(function() {
isMoving=false;
},2000);
}
Basically you have a isMoving variable that is set depending on if your animation or whatever you do is in progress. Even though user scrolls multiple times with mousewheel in one "flick", the function fires only once.

​$(document).ready(function(){
var up=false;
var down=false;
$('#foo').bind('mousewheel', function(e){
if(e.originalEvent.wheelDelta /120 > 0 && up=false) {
up=true;
down=false;
$(this).text('scrolling up !');
}
elseif(e.originalEvent.wheelDelta /120 > 0 && down=false){
down=true;
up=false;
$(this).text('scrolling down !');
}
});
});
And here is a plug in you can use it

Related

How to change this script to autoscroll?

I have a script which has a button to scroll the site but I need it to scroll automatically on page load. I need the script to scroll exactly like shown below, except the button. Could anyone change it for me? I'm new to javascript, thanks..
function scroll(element, speed) {
var distance = element.height();
var duration = distance / speed;
element.animate({scrollTop: distance}, duration, 'linear');
}
$(document).ready(function() {
$("button").click(function() {
scroll($("html, body"), 0.015); // Set as required
});
});
Call the scroll function in on window load, this will scroll the page on load finished.
$(window).on('load', function(){
scroll($("html, body"), 0.015); // Set as required
})
You can try the below JavaScript code
var div = $('.autoscroller');
$('.autoscroller').bind('scroll mousedown wheel DOMMouseScroll mousewheel keyup', function(evt) {
if (evt.type === 'DOMMouseScroll' || evt.type === 'keyup' || evt.type === 'mousewheel') {
}
if (evt.originalEvent.detail < 0 || (evt.originalEvent.wheelDelta && evt.originalEvent.wheelDelta > 0)) {
clearInterval(autoscroller);
}
if (evt.originalEvent.detail > 0 || (evt.originalEvent.wheelDelta && evt.originalEvent.wheelDelta < 0)) {
clearInterval(autoscroller);
}
});
var autoscroller = setInterval(function(){
var pos = div.scrollTop();
if ((div.scrollTop() + div.innerHeight()) >= div[0].scrollHeight) {
clearInterval(autoscroller);
}
div.scrollTop(pos + 1);
}, 50);
here on the load of the page. The text are auto-scrolled upto the end of the page.

Detect touch scroll up or down

I need code same this for touch devices . help me please
$(window).on('DOMMouseScroll mousewheel', function (e) {
if (ScrollEnable) {
if (e.originalEvent.detail > 0 || e.originalEvent.wheelDelta < 0) {
console.log('Down');
} else {
console.log('Up');
}
}
return false;
});
and here is my touch code, But consul just take up i need find down for my website ! what can i do :|
$('body').on({
'touchmove': function(e) {
if (e.originalEvent.touches > 0 || e.originalEvent.touches > 0) {
console.log('Down');
} else {
console.log('Up');
}
}
});
var updated=0,st;
$('body').on({
'touchmove': function(e) {
st = $(this).scrollTop();
if(st > updated) {
console.log('down');
}
else {
console.log('up');
}
updated = st;
}
});
You can use scroll event
var lastScrollTop = 0;
$(window).scroll(function(event){
var st = $(this).scrollTop();
if (st > lastScrollTop){
// downscroll code
} else {
// upscroll code
}
lastScrollTop = st;
});
I know my solution is a bit more generic - it is not dependend on any element, but it might help someone that has encountered the same problem as me.
var touchPos;
// store the touching position at the start of each touch
document.body.ontouchstart = function(e){
touchPos = e.changedTouches[0].clientY;
}
// detect wether the "old" touchPos is
// greater or smaller than the newTouchPos
document.body.ontouchmove = function(e){
let newTouchPos = e.changedTouches[0].clientY;
if(newTouchPos > touchPos) {
console.log("finger moving down");
}
if(newTouchPos < touchPos) {
console.log("finger moving up");
}
}
The only way that I could (and tested) detect scroll down/up on mobile devices (android & ios, touch devices):
(other events such as scroll, mousewheel, DOMMouseScroll, nmousewheel and wheel do not work on mobile devices)
jQuery:
let touchStartPosX = 0;
// Detect Scroll Down and Up in mobile(android|ios)
$(window).on('touchmove', (e) => {
// Different devices give different values with different decimal percentages.
const currentPageX = Math.round(e.originalEvent.touches[0].screenY);
if (touchStartPosX === currentPageX) return;
if (touchStartPosX - currentPageX > 0) {
console.log("down");
} else {
console.log("up");
}
touchStartPosX = currentPageX;
});
Vanilla:
let touchStartPosX = 0;
window.addEventListener('touchmove', (e) => {
// Different devices give different values with different decimal percentages.
const currentPageX = Math.round(e.changedTouches[0].screenY);
if (touchStartPosX === currentPageX) return;
if (touchStartPosX - currentPageX > 0) {
console.log("down");
} else {
console.log("up");
}
touchStartPosX = currentPageX;
});
This w3schools.com documentation would help you out http://www.w3schools.com/jquerymobile/jquerymobile_events_scroll.asp
$(document).on("scrollstop",function(){
alert("Stopped scrolling!");
});

How do I hover on Browser's cancel button?

I am trying to populate a splash screen on my website and it is populating if scroll pos is between 1-120, using following JS code.
Please suggest what should be done if I want to execute this on hover browser's and tab's cancel button?
How to read that, cause $(window).scrollTop(); won't return anything if it is less that 0.
function setHeightToEmergencyContainer () {
var getWindowHeight = $(window).height();
var setHeight = (getWindowHeight - 123)/2;
}
setHeightToEmergencyContainer();
$(window).resize(function() {
setHeightToEmergencyContainer();
});
function addEvent(obj, evt, fn) {
if (obj.addEventListener) {
obj.addEventListener(evt, fn, false);
}
else if (obj.attachEvent) {
obj.attachEvent("on" + evt, fn);
}
}
addEvent(window,"load",function(e) {
addEvent(document, "mouseout", function(e) {
e = e ? e : window.event;
var from = e.relatedTarget || e.toElement;
if (!from || from.nodeName == "HTML") {
// stop your drag event here
// for now we can just use an alert
setHeightToEmergencyContainer();
var scroll = $(window).scrollTop();
console.log("scroll pos :: "+scroll);
if(scroll > 0 && scroll <= 120){
console.log("show popup "+scroll);
$(".tso_pop-container").css({"width":"1366px","height":"700px","overflow":"auto","right":"-296px","top":"106px"});
}
//$.cookie("dontShowUrgencyContainer","yes");
}
});
addEvent(document, "mouseover", function() {
$(".tso_pop-container").css({"width":"0px","height":"0px","overflow":"hidden","right":"50%","top":"50%"});
});
});
//}
window.onblur = function(event) {
$(".tso_pop-container").css({"width":"0px","height":"0px","overflow":"hidden","right":"50%","top":"50%"});
}
first to get scrolled position of document use :
$('body').scrollTop() // webkit
$('html').scrollTop() // moz
for browser hover use :
$(window).mouseenter(function(){
var stop = $('html').scrollTop() == 0 ? $('body').scrollTop() : $('html').scrollTop()
if(stop <= 120){
// your code
}
});
hope this helps you.

Detect Scroll event while already on top

I have a menu bar on the top of my page which i want to show if i scroll up while already on top. Imagine you scroll up, and while beeing there, you scroll up again, the bar would show.
I have this code using jquery
// listen for the scroll to show the top menu
var was_on_top = false;
$(function () {
$(window).bind("scroll", function (e) {
if ($(window).scrollTop() == 0) {
if ($('.menu').css('display') == "none" && was_on_top) {
$('.menu').slideDown();
} else {
was_on_top = true;
}
} else {
was_on_top = false;
}
});
});
But the scroll event does not fire while already on top. Any ideas?
EDIT: Here goes the working code. Tested on FF, Chrome and IE9
// listen for the scroll to show the top menu
var was_on_top = false;
$(function () {
if (window.addEventListener) {
window.addEventListener('DOMMouseScroll', onMouseWheelSpin, false); // FireFox
window.addEventListener('mousewheel', onMouseWheelSpin, false); // Chrome
} else {
window.onmousewheel = onMouseWheelSpin;
}
});
function onMouseWheelSpin(event) {
if (!event) // IE sucks
event = window.event;
if ($(window).scrollTop() == 0 &&
(
event.detail < 0 // Firefox
||
(event.wheelDelta && (
(window.opera && event.wheelDelta < 0) // Opera
||
event.wheelDelta > 0 // IE
)
)
)
) {
if ($('.menu').css('display') == "none" && was_on_top) {
$('.menu').slideDown();
} else {
was_on_top = true;
}
} else {
was_on_top = false;
}
}
The scroll event does not fire, because the window is no longer scrolling.
You will likely need to create a custom event for the mouse wheel itself.
This might be helpful: Javascript: Capture mouse wheel event and do not scroll the page?

Treating each div as a "page" when scrolling

I have a page that I'm building and I would like to make it that when I scroll (up or down) the page scrolls to the next div (each div is 100% the height of the window). And gets "fixed" there until you scroll again. An example of what I'm trying to accomplish can be seen here:
http://testdays.hondamoto.ch/
You will notice that when you scroll down, it automatically moves you to the next "div".
What I've tried:
Using the jQuery .scroll event combined with:
function updatePosition() {
if(canScroll) {
var pageName;
canScroll = false;
var st = $(window).scrollTop();
if (st > lastScrollTop){
// downscroll code
if(pageNumber < 7) {
pageNumber++;
}
pageName = '#' + getPageToScrollTo().id;
$('body').animate({ scrollTop: $(pageName).offset().top }, 2000, function() {
canScroll = true;
});
} else {
// upscroll code
if(pageNumber > 0) {
pageNumber--;
}
pageName = '#' + getPageToScrollTo().id;
$('body').animate({ scrollTop: $(pageName).offset().top }, 2000, function() {
canScroll = true;
});
}
lastScrollTop = st;
}
}
But the scroll event was getting called when the page was scrolling (animating), AND when the user scrolled. I only need it to be called when the user scrolls.
Then I added:
var throttled = _.throttle(updatePosition, 3000);
$(document).scroll(throttled);
From the Underscore.js library - but it still did the same.
Finally, I browsed here a bit and found:
Call Scroll only when user scrolls, not when animate()
But I was unable to implement that solution. Is there anyone that knows of any libraries or methods to get this working?
EDIT:
Solution based on Basic's answer:
function nextPage() {
canScroll = false;
if(pageNumber < 7) {
pageNumber++;
}
pageName = getPageToScrollTo();
$('html, body').stop().animate({ scrollTop: $(pageName).offset().top }, 1000, function() {
canScroll = true;
});
}
function prevPage() {
canScroll = false;
if(pageNumber > 0) {
pageNumber--;
}
pageName = getPageToScrollTo();
$('html, body').stop().animate({ scrollTop: $(pageName).offset().top }, 1000, function() {
canScroll = true;
});
}
//--Bind mouseWheel
$(window).on(mousewheelevt, function(event) {
event.preventDefault();
if(canScroll){
if(mousewheelevt == "mousewheel") {
if (event.originalEvent.wheelDelta >= 0) {
prevPage();
} else {
nextPage();
}
} else if(mousewheelevt == "DOMMouseScroll") {
if (event.originalEvent.detail >= 0) {
nextPage();
} else {
prevPage();
}
}
}
});
Ok...
The relevant code for the Honda site can be found in http://testdays.hondamoto.ch/js/script_2.js. It seems to be doing some calculations to locate the top of the div then scroll to it. There are handlers for different types of scrolling.
Specifically, the movement is handled by function navigation(target)
the key bits is here...
$('html,body').stop().animate({
scrollTop: $(target).offset().top + newMargin
}, 1000,'easeInOutExpo',function(){
//Lots of "page"-specific stuff
}
});
There are handlers for the scroll types...
$('body').bind('touchstart', function(event) {
//if(currentNav!=3){
// jQuery clones events, but only with a limited number of properties for perf reasons. Need the original event to get 'touches'
var e = event.originalEvent;
scrollStartPos = e.touches[0].pageY;
//}
});
//--Bind mouseWheel
$('*').bind('mousewheel', function(event, delta) {
event.preventDefault();
//trace('class : '+$(this).attr('class') + ' id : '+$(this).attr('id'));
if(!busy && !lockScrollModel && !lockScrollMap){
if(delta<0){
nextPage();
}else{
prevPage();
}
}
});
You'll note that the navigate() function sets a busy flag which is unset when scrolling completes - which is how it suppresses all new scroll events during a scroll. Try changing the direction of scroll while the page is already scrolling and you'll notice user input is being ignored too.

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