How should I do to get the scrolling direction using onScrollStart and not onScrollEnd?
For now, here is the code I found for onScrollEnd :
var current_page = 1;
var old_page = 0;
funnction load() {
myScrollH = new iScroll('wrapper', {
onScrollEnd: function () {
current_page = this.currPageX+1
if(old_page<current_page) {
console.log('right');
}
else if (old_page>current_page) {
console.log('left');
};
old_page=current_page;
}
})
};
load();
If someone has the answer...
Tchuss !
V.
During onScrollStart, the event Scroll is not fired. So its not possible (i think) to implement the same.
Only on onScrollEnd, the Scroll Event is fired which has the direction.
Related
I have a slider and I made a code that goes next and prev with mouse scroll. But it doesn't work well with mac and touchpad. how can I fix it? Can I put some delay or something I tried to use some setTimeout but it didn't work well or I didn't do it right.
$('#body').on('mousewheel', function (event) {
if (typeof event.originalEvent.wheelDeltaY === 'undefined') {
console.log("could not find mouse deltas")
}
var deltaY = event.originalEvent.wheelDeltaY;
var scrolledUp = deltaY < 0;
var scrolledDown = deltaY > 0;
if (scrolledDown) {
if (swiper_color.activeIndex > 2) {
goTop();
activeIndexToTwo();
} else {
swiper_color.slidePrev();
swiper_image.slidePrev();
swiper_desc.slidePrev();
swiper_title.slidePrev();
swiper_jar.slidePrev();
}
}
if (scrolledUp) {
if (swiper_color.activeIndex < 2) {
swiper_color.slideNext();
swiper_image.slideNext();
swiper_desc.slideNext();
swiper_title.slideNext();
swiper_jar.slideNext();
} else {
checkscroll();
}
}
});
I'd recommend throttling the function. You could write a throttle function, or use one from a library like Lodash (Lodash throttle docs)
function yourFn (event) {
// ... all of your js here
// ...
}
$('#body').on('mousewheel', _.throttle(yourFn, 100));
The 100(ms) above means your function can only fire every 100ms, feel free to modify the time to your liking.
I am trying to create a website that automatically scrolls to each section upon a single scroll action. This means that the code has to check if the page is scrolled up or scrolled down. I believe the code below solves my problem but the scroll action is fired more than once while the page is scrolling. You will see that the first alert in the if statement reaches 5 instead of the desired 1. Any help on the matter would be highly appreciated.
[Note] I am using the velocity.js library to scroll to each section within the container.
var page = $("#content-container");
var home = $("#home-layer-bottom");
var musicians = $("#musicians");
var athletes = $("#athletes");
var politics = $("#politics");
var bio = $("#politics");
var pages = [ home,musicians,athletes,politics,bio ];
var pageCur = 0;
var lastScrollTop = 0;
page.scroll(function(){
var st = $(this).scrollTop();
var pageNex = pageCur + 1;
if (st > lastScrollTop){
alert(pageNex);
pages[pageNex].velocity("scroll", { container: $("#content-container") });
} else {
alert(pageCur-1);
pages[pageCur-1].velocity("scroll", { container: $("#content-container") });
}
lastScrollTop = st;
pageCur = pageNex;
});
The scroll event (as well as the resize event) fire multiple times as a user does this. To help this, the best practice is to debounce. However, I've never gotten that to work. Instead, I use a global boolean to check if the function has fired.
var scrolled = false;
page.on('scroll', function(){
if(!scrolled){
scrolled = true;
//do stuff that should take a while...
scrolled = false;
};
});
This worked for me!
var ScrollDebounce = true;
$('.class').on('scroll',
function () {
if (ScrollDebounce) {
ScrollDebounce = false;
//do stuff
setTimeout(function () { ScrollDebounce = true; }, 500);
}
})
I have to do some Special things for my Webpage to work on Android the correct way. Some Images are displayed (one visible, the other unvisible) and through swipe it should be possible to Change them. No Problem so far on all OS.
But it also should be possible to zoom. Now Android starts to be Buggy. It stops the zoom-gesture because of the swipe callback. The callback itself doesn't Change the page because the view is zoomed, so there should be no break.
Now I work arround through turning my swipeleft and swiperight off while two fingers touching the Display, and tourning back on if the fingers leave the Display.
On First run I can swipe, then I can zoom with no break, but then I can't swipe anymore. The function to set the callbacks back on again is called, it set's the callbacks, but they won't be executed...
Here's the code:
app.utils.scroll = (function(){
var $viewport = undefined;
var swipeDisabled = false;
var init = function(){
$viewport = $('#viewport');
$viewport.mousewheel(mayChangePage);
// On touchstart with two fingers, remove the swipe listeners.
$viewport.on('touchstart', function (e) {
if (e.originalEvent.touches.length > 1) {
removeSwipe();
swipeDisabled = true;
}
});
// On touchend, re-define the swipe listeners, if they where removed through two-finger-gesture.
$viewport.on('touchend', function (e) {
if (swipeDisabled === true) {
swipeDisabled = false;
initSwipe();
}
});
initSwipe();
}
var mayChangePage = function(e){
// If page is not zoomed, change page (next or prev).
if (app.utils.zoom.isZoomed() === false) {
if (e.deltaY > 0) {
app.utils.pagination.prev(e);
} else {
app.utils.pagination.next(e);
}
}
// Stop scrolling page through mouse wheel.
e.preventDefault();
e.stopPropagation();
};
var next = function (e) {
// If page is not zoomed, switch to next page.
if (app.utils.zoom.isZoomed() === false) {
app.utils.pagination.next(e);
}
};
var prev = function (e) {
// If page is not zoomed, switch to prev page.
if (app.utils.zoom.isZoomed() === false) {
app.utils.pagination.prev(e);
}
};
var initSwipe = function () {
// Listen to swipeleft / swiperight-Event to change page.
$viewport.on('swipeleft.next', next);
$viewport.on('swiperight.prev', prev);
};
var removeSwipe = function () {
// Remove listen to swipeleft / swiperight-Event for changing page to prevent android-bug.
$viewport.off('swipeleft.next');
$viewport.off('swiperight.prev');
};
$(document).ready(init);
}());
Pastebin
Any ideas what I can do to get the Events back on again?
Thanks for all Ideas.
Regards
lippoliv
Fixed it:
jQuery Mobile itself prevents the swipe Event if an handler is registered, to kill an "scroll".
So I overwrote the $.event.special.swipe.scrollSupressionThreshold value and set it to 10000, to prevent jQueryMobile's preventDefault-call:
$.event.special.swipe.scrollSupressionThreshold = 10000;
Now my Code Looks like
app.utils.scroll = (function(){
var $viewport = undefined;
var swipeDisabled = false;
var init = function(){
$viewport = $('#viewport');
$viewport.mousewheel(mayChangePage);
// See #23.
$.event.special.swipe.scrollSupressionThreshold = 10000;
// Listen to swipeleft / swiperight-Event to change page.
$viewport.on('swipeleft.next', next);
$viewport.on('swiperight.prev', prev);
}
var mayChangePage = function(e){
// If page is not zoomed, change page (next or prev).
if (app.utils.zoom.isZoomed() === false) {
if (e.deltaY > 0) {
app.utils.pagination.prev(e);
} else {
app.utils.pagination.next(e);
}
}
// Stop scrolling page through mouse wheel.
e.preventDefault();
e.stopPropagation();
};
var next = function (e) {
// If page is not zoomed, switch to next page.
if (app.utils.zoom.isZoomed() === false) {
app.utils.pagination.next(e);
}
};
var prev = function (e) {
// If page is not zoomed, switch to prev page.
if (app.utils.zoom.isZoomed() === false) {
app.utils.pagination.prev(e);
}
};
$(document).ready(init);
}());
Thanks to Omar- who wrote with me several minutes / hours in the jquery IRC and gave some suggestions regarding overwriting Standard values for jQueryMobile.
So, I'd like to fire a function only once on scroll (using Scrollstop, given by a stackoverflow answer)
The problem is that I don't get to fire the function only once. I've tried different solutions ( .on(), setting a counter, setting it outside/inside the window.scrollstop function) but nothing worked.
I don't think it's difficult, but.. I didn't get to make it work so far.
Here's the plugin I'm using
$.fn.scrollStopped = function(callback) {
$(this).scroll(function(){
var self = this, $this = $(self);
if ($this.data('scrollTimeout')) {
clearTimeout($this.data('scrollTimeout'));
}
$this.data('scrollTimeout', setTimeout(callback,300,self));
});
};
and here's my code:
$(window).scrollStopped(function(){
if ($(".drawing1").withinViewport()) {
doNothing()
}
})
var doNothing = function() {
$('#drawing1').lazylinepainter('paint');
}
(removed the counter since it didn't work)
Live demo here
PS: the function I'd like to make happen only once is the lazyPaint. It begins when we scroll to the element but it fires once again when it ends.
Here's my version of having a function fire once while listening to the scroll event:
var fired = false;
window.addEventListener("scroll", function(){
if (document.body.scrollTop >= 1000 && fired === false) {
alert('This will happen only once');
fired = true;
}
}, true)
how about using a variable to see whether it was previously fired:
var fired = 0;
$.fn.scrollStopped = function(callback) {
$(this).scroll(function(){
if(fired == 0){
var self = this, $this = $(self);
if ($this.data('scrollTimeout')) {
clearTimeout($this.data('scrollTimeout'));
}
$this.data('scrollTimeout', setTimeout(callback,300,self));
fired = 1;
}
});
};
These anwsers didn't work for me so here's my code:
var fired = 0;
jQuery(this).scroll(function(){
if(fired == 0){
alert("fired");
fired = 1;
}
});
How about this solution?
function scrollEvent() {
var hT = $('#scroll-to').offset().top,
hH = $('#scroll-to').outerHeight(),
wH = $(window).height(),
wS = $(this).scrollTop();
if (wS > (hT+hH-wH)){
console.log('H1 on the view!');
window.removeEventListener("scroll", scrollEvent);
}
}
window.addEventListener("scroll", scrollEvent);
The question is a bit old, but as it popped up first when I search for "addeventlistener scroll once", I will add this reply. There is now a { once: true } parameter to only trigger an event once.
window.addEventListener("scroll", () => {
/* your code here */
}, { once: true });
I'm trying to build a Javascript listener for a small page that uses AJAX to load content based on the anchor in the URL. Looking online, I found and modified a script that uses setInterval() to do this and so far it works fine. However, I have other jQuery elements in the $(document).ready() for special effects for the menus and content. If I use setInterval() no other jQuery effects work. I finagled a way to get it work by including the jQuery effects in the loop for setInterval() like so:
$(document).ready(function() {
var pageScripts = function() {
pageEffects();
pageURL();
}
window.setInterval(pageScripts, 500);
});
var currentAnchor = null;
function pageEffects() {
// Popup Menus
$(".bannerMenu").hover(function() {
$(this).find("ul.bannerSubmenu").slideDown(300).show;
}, function() {
$(this).find("ul.bannerSubmenu").slideUp(400);
});
$(".panel").hover(function() {
$(this).find(".panelContent").fadeIn(200);
}, function() {
$(this).find(".panelContent").fadeOut(300);
});
// REL Links Control
$("a[rel='_blank']").click(function() {
this.target = "_blank";
});
$("a[rel='share']").click(function(event) {
var share_url = $(this).attr("href");
window.open(share_url, "Share", "width=768, height=450");
event.preventDefault();
});
}
function pageURL() {
if (currentAnchor != document.location.hash) {
currentAnchor = document.location.hash;
if (!currentAnchor) {
query = "section=home";
} else {
var splits = currentAnchor.substring(1).split("&");
var section = splits[0];
delete splits[0];
var params = splits.join("&");
var query = "section=" + section + params;
}
$.get("loader.php", query, function(data) {
$("#load").fadeIn("fast");
$("#content").fadeOut(100).html(data).fadeIn(500);
$("#load").fadeOut("fast");
});
}
}
This works fine for a while but after a few minutes of the page being loaded, it drags to a near stop in IE and Firefox. I checked the FF Error Console and it comes back with an error "Too many Recursions." Chrome seems to not care and the page continues to run more or less normally despite the amount of time it's been open.
It would seem to me that the pageEffects() call is causing the issue with the recursion, however, any attempts to move it out of the loop breaks them and they cease to work as soon as setInterval makes it first loop.
Any help on this would be greatly appreciated!
I am guessing that the pageEffects need added to the pageURL content.
At the very least this should be more efficient and prevent duplicate handlers
$(document).ready(function() {
pageEffects($('body'));
(function(){
pageURL();
window.setTimeout(arguments.callee, 500);
})();
});
var currentAnchor = null;
function pageEffects(parent) {
// Popup Menus
parent.find(".bannerMenu").each(function() {
$(this).unbind('mouseenter mouseleave');
var proxy = {
subMenu: $(this).find("ul.bannerSubmenu"),
handlerIn: function() {
this.subMenu.slideDown(300).show();
},
handlerOut: function() {
this.subMenu.slideUp(400).hide();
}
};
$(this).hover(proxy.handlerIn, proxy.handlerOut);
});
parent.find(".panel").each(function() {
$(this).unbind('mouseenter mouseleave');
var proxy = {
content: panel.find(".panelContent"),
handlerIn: function() {
this.content.fadeIn(200).show();
},
handlerOut: function() {
this.content.slideUp(400).hide();
}
};
$(this).hover(proxy.handlerIn, proxy.handlerOut);
});
// REL Links Control
parent.find("a[rel='_blank']").each(function() {
$(this).target = "_blank";
});
parent.find("a[rel='share']").click(function(event) {
var share_url = $(this).attr("href");
window.open(share_url, "Share", "width=768, height=450");
event.preventDefault();
});
}
function pageURL() {
if (currentAnchor != document.location.hash) {
currentAnchor = document.location.hash;
if (!currentAnchor) {
query = "section=home";
} else {
var splits = currentAnchor.substring(1).split("&");
var section = splits[0];
delete splits[0];
var params = splits.join("&");
var query = "section=" + section + params;
}
var content = $("#content");
$.get("loader.php", query, function(data) {
$("#load").fadeIn("fast");
content.fadeOut(100).html(data).fadeIn(500);
$("#load").fadeOut("fast");
});
pageEffects(content);
}
}
Thanks for the suggestions. I tried a few of them and they still did not lead to the desirable effects. After some cautious testing, I found out what was happening. With jQuery (and presumably Javascript as a whole), whenever an AJAX callback is made, the elements brought in through the callback are not binded to what was originally binded in the document, they must be rebinded. You can either do this by recalling all the jQuery events on a successful callback or by using the .live() event in jQuery's library. I opted for .live() and it works like a charm now and no more recursive errors :D.
$(document).ready(function() {
// Popup Menus
$(".bannerMenu").live("hover", function(event) {
if (event.type == "mouseover") {
$(this).find("ul.bannerSubmenu").slideDown(300);
} else {
$(this).find("ul.bannerSubmenu").slideUp(400);
}
});
// Rollover Content
$(".panel").live("hover", function(event) {
if (event.type == "mouseover") {
$(this).find(".panelContent").fadeIn(200);
} else {
$(this).find(".panelContent").fadeOut(300);
}
});
// HREF Events
$("a[rel='_blank']").live("click", function(event) {
var target = $(this).attr("href");
window.open(target, "_blank");
event.preventDefault();
});
$("a[rel='share']").live("click", function(event) {
var share_url = $(this).attr("href");
window.open(share_url, "Share", "width=768, height=450");
event.preventDefault();
});
setInterval("checkAnchor()", 500);
});
var currentAnchor = null;
function checkAnchor() {
if (currentAnchor != document.location.hash) {
currentAnchor = document.location.hash;
if (!currentAnchor) {
query = "section=home";
} else {
var splits = currentAnchor.substring(1).split("&");
var section = splits[0];
delete splits[0];
var params = splits.join("&");
var query = "section=" + section + params;
}
$.get("loader.php", query, function(data) {
$("#load").fadeIn(200);
$("#content").fadeOut(200).html(data).fadeIn(200);
$("#load").fadeOut(200);
});
}
}
Anywho, the page works as intended even in IE (which I rarely check for compatibility). Hopefully, some other newb will learn from my mistakes :p.