Angular 8 window scroll events not firing on mobile browsers - javascript

I have tried almost every solution that is available online but nothing worked out, below are few solutions I tried
My actual scenario is to show a specific div element when the other div element goes off from the screen when the screen is scrolled down.
I'm able to do this on desktops/laptops but not on mobiles where the scroll event doesn't fire at all.
my Desktop / Laptop scroll event listener I'm using is
#HostListener('window:scroll', ['$event']) getScrollHeight(event) {
console.log('from desk' , window.pageYOffset, event);
}
While for the mobile as my scroll event doesn't fire so I used below
#HostListener('window:touchStart', ['$event']) checkTouchEnd(event) {
this.start = event.changedTouches[0];
});
#HostListener('window:touchend', ['$event']) checkTouchEnd(event) {
this.end = event.changedTouches[0];
let scrollpositionValue;
if((this.end.screenY - this.start.screenY) > 0) {
console.log('scrolling up');
console.log('[scroll-up]', this.end.screenY - this.start.screenY);
scrollpositionValue = this.end.screenY - this.start.screenY;
} else if(this.end.screenY - this.start.screenY < 0) {
console.log('scrolling down');
console.log('[scroll-down]', this.end.screenY - this.start.screenY);
scrollpositionValue = this.end.screenY - this.start.screenY;
}
const scrollPosition = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop || 0;
console.log('[scroll]', scrollPosition);
});
Can somebody help me with a solution, All I want is to get the scrollY position on a mobile browser scrolled.
thanks in advance!

My actual scenario is to show a specific div element when the other div element goes off from the screen when the screen is scrolled down.
Don't use scroll event listener for this, use Intersection Observer (IO) for this.
this was designed for such problems. With IO you can react whenever an HTML element intersects with another one (or with the viewport)
Check this page, it shows you how to animate an element once it comes into viewport (scroll all the way down)
Short recap on what you have to do:
First you have to create a new observer:
var options = {
rootMargin: '0px',
threshold: 1.0
}
var observer = new IntersectionObserver(callback, options);
Here we define that once your target Element is 100% visible in the viewport (threshold of 1) your callback Function is getting executed. Here you can define another percentage, 0.5 would mean that the function would be executed once your element is 50% visible.
Then you have to define which elements to watch
var target = document.querySelector('.div-to-watch');
observer.observe(target);
Last you need to specify what should happen once the element is visible in your viewport by defining the callback function:
var callback = function(entries, observer) {
entries.forEach(entry => {
// Each entry describes an intersection change for one observed
// here you animate another element and do whatever you like
});
};
If you need to support older browsers, use the official polyfill from w3c.
If you don't want to trigger the animation again when the elements are scrolled again into view a second time then you can also unobserve an element once it's animated.

Related

Stop script if users scrolls

Disclaimer: I am not a JavaScript developer, I'm a web designer. HTML and CSS, I handle all day, JS, not so much. That's why I'm reaching out for help.
The following script allows for a smooth scroll to the top of the page:
function scrollToTop() {
var position =
document.body.scrollTop || document.documentElement.scrollTop;
if (position) {
window.scrollBy(0, -Math.max(1, Math.floor(position / 10)));
scrollAnimation = setTimeout("scrollToTop()", 30);
} else clearTimeout(scrollAnimation);
}
Is there a way to "stop" the script from executing if the user decides to scroll back down the moment the script is running and taking the user back to the top of the page?
Here's a demo for reference: https://codepen.io/ricardozea/pen/ewBzyO
Thank you.
To specifically detect scrolling back down the page, you could check the old postion against the current position and ensure the scroll is moving in the intended direction:
function scrollToTop(prevPosition) {
// first time round, prevPosition is undefined
var position =
document.body.scrollTop || document.documentElement.scrollTop;
// did page move in non-expected direction? If so, bail-out
if (prevPosition <= position) {
return;
}
var scrollAnimation; //declare this so it doesn't leak onto global scope
if (position) {
var scrollAmt = -Math.max(1, Math.floor(position / 10));
window.scrollBy(0, scrollAmt);
// After timeout, re-call the function with current position.
// Becomes prevPosition for the next time round
scrollAnimation = setTimeout(() => scrollToTop(position), 30);
} else clearTimeout(scrollAnimation);
}
See https://codepen.io/spender/pen/eYvRyox
Why not listen to wheel events? This won't detect dragging the scrollbar with the mouse.
Thanks a lot for your answers!
After consulting with a friend of mine, he provided me with a much succinct way to accomplish the overall behavior of smooth scrolling to the top while solving the potential case of a user wanting to scroll back down during the animation.
Just add this script to a <button> element in the onclick: attribute:
window.scrollTo({top: 0, behavior: "smooth"});
It looks like this:
<button onclick='window.scrollTo({top: 0, behavior: "smooth"});'>Back to Top ↑</button>
Here's a new demo: https://codepen.io/ricardozea/pen/NWpgyjL

How to check each new scroll and avoid Apple mouses issue (multiple-scroll effect)

I try to make a mousewheel event script, but getting some issues since I'm using an Apple Magic Mouse and its continue-on-scroll function.
I want to do this http://jsfiddle.net/Sg8JQ/ (from jQuery Tools Scrollable with Mousewheel - scroll ONE position and stop, using http://brandonaaron.net/code/mousewheel/demos), but I want a short animation (like 250ms) when scrolling to boxes, AND ability to go throught multiple boxes when scrolling multiple times during one animation. (If I scroll, animation start scrolling to second box, but if I scroll again, I want to go to the third one, and if I scroll two times, to the forth, etc.)
I first thought stopPropagation / preventDefault / return false; could "stop" the mousewheel velocity (and the var delta) – so I can count the number of new scroll events (maybe with a timer) –, but none of them does.
Ideas?
EDIT : If you try to scroll in Google Calendars with these mouses, several calendars are switched, not only one. It seems they can't fix that neither.
EDIT 2 : I thought unbind mousewheel and bind it again after could stop the mousewheel listener (and don't listen to the end of inertia). It did not.
EDIT 3 : tried to work out with Dates (thanks to this post), not optimal but better than nothing http://jsfiddle.net/eZ6KE/
Best way is to use a timeout and check inside the listener if the timeout is still active:
var timeout = null;
var speed = 100; //ms
var canScroll = true;
$(element).on('DOMMouseScroll mousewheel wheel', function(event) {
// Timeout active? do nothing
if (timeout !== null) {
event.preventDefault();
return false;
}
// Get scroll delta, check for the different kind of event indexes regarding delta/scrolls
var delta = event.originalEvent.detail ? event.originalEvent.detail * (-120) : (
event.originalEvent.wheelDelta ? event.originalEvent.wheelDelta : (
event.originalEvent.deltaY ? (event.originalEvent.deltaY * 1) * (-120) : 0
));
// Get direction
var scrollDown = delta < 0;
// This is where you do something with scrolling and reset the timeout
// If the container can be scrolling, be sure to prevent the default mouse action
// otherwise the parent container can scroll too
if (canScroll) {
timeout = setTimeout(function(){timeout = null;}, speed);
event.preventDefault();
return false;
}
// Container couldn't scroll, so let the parent scroll
return true;
});
You can apply this to any scrollable element and in my case, I used the jQuery tools scrollable library but ended up heavily customizing it to improve browser support as well as adding in custom functionality specific to my use case.
One thing you want to be careful of is ensuring that the timeout is sufficiently long enough to prevent multiple events from triggering seamlessly. My solution is effective only if you want to control the scrolling speed of elements and how many should be scrolled at once. If you add console.log(event) to the top of the listener function and scroll using a continuous scrolling peripheral, you will see many mousewheel events being triggered.
Annoyingly the Firefox scroll DOMMouseScroll does not trigger on magic mouse or continuous scroll devices, but for normal scroll devices that have a scroll and stop through the clicking cycle of the mouse wheel.
I had a similar problem on my website and after many failed attempts, I wrote a function, which calculated total offset of selected box and started the animation over. It looked like this:
function getOffset() {
var offset = 0;
$("#bio-content").children(".active").prevAll().each(function (i) {
offset += $(this)[0].scrollHeight;
});
offset += $("#bio-content").children(".active")[0].scrollHeight;
return offset;
}
var offset = getOffset();
$('#bio-content').stop().animate( {
scrollTop: offset
}, animationTime);
I hope it gives you an idea of how to achieve what you want.
you can try detecting when wheel stops moving, but it would add a delay to your response time
$(document).mousewheel(function() {
clearTimeout($.data(this, 'timer'));
$.data(this, 'timer', setTimeout(function() {
alert("Haven't scrolled in 250ms!");
//do something
}, 250));
});
source:
jquery mousewheel: detecting when the wheel stops?
or implement flags avoiding the start of a new animation
var isAnimating=false;
$(document).bind("mousewheel DOMMouseScroll MozMousePixelScroll", function(event, delta) {
event.preventDefault();
if (isAnimating) return;
navigateTo(destination);
});
function navigateTo(destination){
isAnimating = true;
$('html,body').stop().animate({scrollTop: destination},{complete:function(){isAnimating=false;}});
}

How use JQuery/Javascript to scroll down a page when the cursor at the top or bottom edge of the screen?

Simple, I just would like to have it so when a user is dragging an item and they reach the very bottom or top of the viewport (10px or so), the page (about 3000px long) gently scrolls down or up, until they move their cursor (and thus the item being dragged) out of the region.
An item is an li tag which uses jquery to make the list items draggable. To be specific:
../jquery-ui-1.8.14.custom.min.js
http://code.jquery.com/jquery-1.6.2.min.js
I currently use window.scrollBy(x=0,y=3) to scroll the page and have the variables of:
e.pageY ... provides absolute Y-coordinates of cursor on page (not relative to screen)
$.scrollTop() ... provides offset from top of page (when scroll bar is all the way up, it is 0)
$.height()... provides the height of viewable area in the user's browser/viewport
body.offsetHeight ... height of the entire page
How can I achieve this and which event best accommodates this (currently its in mouseover)?
My ideas:
use a an if/else to check if it is in top region or bottom, scroll up if e.pageY is showing it is in the top, down if e.page& is in bottom, and then calling the $('li').mouseover() event to iterate through...
Use a do while loop... this has worked moderately well actually, but is hard to stop from scrolling to far. But I am not sure how to control the iterations....
My latest attempt:
('li').mouseover(function(e) {
totalHeight = document.body.offsetHeight;
cursor.y = e.pageY;
var papaWindow = window;
var $pxFromTop = $(papaWindow).scrollTop();
var $userScreenHeight = $(papaWindow).height();
var iterate = 0;
do {
papaWindow.scrollBy(0, 2);
iterate++;
console.log(cursor.y, $pxFromTop, $userScreenHeight);
}
while (iterate < 20);
});
Works pretty well now, user just needs to "jiggle" the mouse when dragging items sometimes to keep scrolling, but for scrolling just with mouse position its pretty solid. Here is what I finally ended up using:
$("li").mouseover(function(e) {
e = e || window.event; var cursor = { y: 0 }; cursor.y = e.pageY; //Cursor YPos
var papaWindow = parent.window;
var $pxFromTop = $(papaWindow).scrollTop();
var $userScreenHeight = $(papaWindow).height();
if (cursor.y > (($userScreenHeight + $pxFromTop) / 1.25)) {
if ($pxFromTop < ($userScreenHeight * 3.2)) {
papaWindow.scrollBy(0, ($userScreenHeight / 30));
}
}
else if (cursor.y < (($userScreenHeight + $pxFromTop) * .75)) {
papaWindow.scrollBy(0, -($userScreenHeight / 30));
}
}); //End mouseover()
This won't work as the event only fires while you're mouse is over the li.
('li').mouseover(function(e) { });
You need to be able to tell the position of the mouse relative to the viewport when an item is being dragged. When the users starts to drag an item attach an 'mousemove' event to the body and then in that check the mouse position and scroll when necessary.
$("body").on("mousemove", function(event) {
// Check mouse position - scroll if near bottom or top
});
Dont forget to remove your event when the user stops dragging.
$("body").off("mousemove", function(event) {
// Check mouse position - scroll if near bottom or top
});
This may not be exactly what you want, but it might help. It will auto-scroll when the mouse is over the 'border of the screen' (a user defined region). Say you have a 40px wide bar on the right of the screen, if the mouse reaches the first 1px, it will start scrolling. Each px you move into it, the speed will increase. It even has a nice easing animation.
http://www.smoothdivscroll.com/v1-2.htm
I get a weekly newsletter (email) from CodeProject, and it had some stuff that certainly looks like it will solve my problem... hopefully this can help others:
http://johnpolacek.github.com/scrollorama/ -- JQuery based and animates the scroll
https://github.com/IanLunn/jQuery-Parallax -- JQuery based, similar to above
http:// remysharp. com/2009/01/26/element-in-view-event-plugin/ -- JQuery, detects whether an element is currently in view of the user (super helpful for this issue!)
Also the site in #2 had some interesting code:
var windowHeight = $window.height();
var navHeight = $('#nav').height() / 2;
var windowCenter = (windowHeight / 2);
var newtop = windowCenter - navHeight;
//ToDo: Find a way to use these vars and my original ones to determine scroll regions

<select> drop down flashing on focus in iphone browser with iScroll4 script

See this demo page in iphone http://jsbin.com/unese4/8 at the bottom of the page there is one dropdown which opens but doesn't work properly.
This question is related to this question iScroll 4 not working with form <select> element iPhone Safari and Android browser
Actually, your issue is related to this question:
webkit-transform issue on safari using select elements
When an input gains focus in iOS Safari, it checks if the input is in view. If it isn’t, Safari forcibly scrolls the document, and the element(s) which contain the input, to make it visible.
iScroll uses a CSS transform to move the scrollable area around, and it looks like Safari’s behavior is broken for selects — it doesn't notice the transform, thinks that the select is out of view, and scrolls its container (#scrollable) to make it visible (again, not accounting for the transform), which puts it way out of view.
This is fundamentally an iOS bug, and should be reported to Apple by as many web developers as are affected by the issue! A workaround can be implemented most effectively inside iScroll, so I encourage you to report the issue to its developers.
That said, I have come up with a workaround, which you'll find at the bottom of this answer. You can use it by calling it, once, with your instance of iScroll:
workAroundiScrollSelectPositioning(myScroll);
A live demo is at your jsbin paste here. It triggers when a select gains focus, and does three things:
Remembers the scroll position, and tells iScroll to immediately scroll to the top left corner (removing any transform), and sets the top and left CSS properties of the scroll area to the current scroll position. Visually, everything looks the same, but the scroll area is now positioned in a way that Safari will see.
Block iScroll from seeing any touches (this is ugly, but it stops iScroll from applying a transform on the scroll area while we have it repositioned).
When the select loses focus, put everything back to the way it was (restore the original position and transform and stop blocking iScroll).
There are still cases where the element's position can get screwed up (e.g. when a textarea has focus but is only partially in view, and you type and cause Safari to try to bring the rest of it in view), but these are best fixed in iScroll.
function workAroundiScrollSelectPositioning(iscroll){
iscroll.scroller.addEventListener('focusin', function(e){
if (e.target.tagName === 'SELECT') {
var touchEvent = 'ontouchstart' in window ? 'touchmove' : 'mousemove',
touchListener = {
handleEvent: function(e){
e.stopPropagation();
e.stopImmediatePropagation();
}
},
blurListener = {
oldX: iscroll.x,
oldY: iscroll.y,
handleEvent: function(e){
iscroll.scroller.style.top = '';
iscroll.scroller.style.left = '';
iscroll.scrollTo(this.oldX, this.oldY, 0);
e.target.removeEventListener('blur', blurListener, false);
iscroll.scroller.removeEventListener(touchEvent, touchListener, true);
}
};
iscroll.scroller.style.top = iscroll.y + 'px';
iscroll.scroller.style.left = iscroll.x + 'px';
iscroll.scrollTo(0, 0, 0);
e.target.addEventListener('blur', blurListener, false);
iscroll.scroller.addEventListener(touchEvent, touchListener, true);
}
}, false);
}
you can use a custom table view on that place, suppose you want to show drop down list when user click on textfield.
so when the user clcik on the textfield the delegate method get called TextFieldBeginEditing and inside that create a small table view . that look like a drop down list ...
This is modified function workAroundiScrollSelectPositioning that worked for me.
function workAroundiScrollSelectPositioning(iscroll){
var touchEvent = 'ontouchstart' in window ? 'touchstart' : 'mousemove',
oldX, oldY;
iscroll.scroller.addEventListener('focusin', function(e){
if (e.target.tagName === 'SELECT') {
var blurListener = {
oldX: oldX,
oldY: oldY,
handleEvent: function(e){
iscroll.scroller.style['margin-top'] = '';
iscroll.scroller.style.left = '';
iscroll.scrollTo(oldX, oldY, 0);
e.target.removeEventListener('blur', blurListener, false);
}
};
iscroll.scroller.style['margin-top'] = oldY + 'px';
iscroll.scroller.style.left = oldX + 'px';
iscroll.scrollTo(0, 0, 0);
e.target.addEventListener('blur', blurListener, false);
}
}, false);
iscroll.scroller.addEventListener(touchEvent, {
handleEvent: function(e){
if (e.target.tagName === 'SELECT') {
oldX = iscroll.x,
oldY = iscroll.y;
e.stopPropagation();
e.stopImmediatePropagation();
}
}
}, true);}

How can I make page scrolling trigger mouseover events?

When the mouse starts hovering over an element because of scrolling (either by wheel, or by keyboard scrolling), it does not trigger a mouseover event on the elements it is hovering (Chrome 6 on OSX). What would be an elegant way to trigger the mouseover event for the correct elements when scrolling?
Honestly, this is gonna be a pain. You'll have to
determine the size and position of every element that should get a mouseover handler.
add a scroll listener to the window.
In the handler, get the mouse cursor position and pageOffset.
Find out which element(s) the cursor is in.
manually call the actual mouseover handler
(Find out which elements the cursor has left, if you want some mouseout behaviour too)
You may need to re-calculate the elements' positions and sizes if they are dynamic. (move 1. beneath 3.)
While this should work fine with block-level elements, I have absolutely no idea on a solution for inline elements.
This is much more simple in the modern day web using document.elementsFromPoint:
Add a scroll listener to the window.
In the handler, call document.elementsFromPoint.
Manually call the actual pointerover handler for those elements. Keep track of these elements.
(optionally) Manually call the actual pointermove handler for those elements.
Check the list of elements from the previous time around. Manually call the actual pointerleave handler for elements no longer being hovered.
Here's some psuedo-code:
let prevHoveredEls = [];
document.addEventListener("scroll", (e) => {
let hoveredEls = document.elementsFromPoint(e.pageX, e.pageY);
hoveredEls = hoveredEls.filter(
(el) => el.classList.contains("elements-cared-about")
);
const notHoveredEls = prevHoveredEls.filter(
(el) => !prevHoveredEls.includes(el)
);
hoveredEls.forEach((el) => {
const bcr = el.getBoundingClientRect();
el.handlePointerEnter({
layerX: e.pageX - bcr.left,
layerY: e.pageY - bcr.top,
});
});
notHoveredEls.forEach((el) => {
const bcr = el.getBoundingClientRect();
el.handlePointerLeave({
layerX: e.pageX - bcr.left,
layerY: e.pageY - bcr.top,
});
});
prevHoveredEls = hoveredEls;
});
Try some hack like myDiv.style.opacity = 1+Math.random(); on scroll ;)

Categories

Resources