How can I get and set the current web page scroll position?
I have a long form which needs to be refreshed based on user actions/input. When this happens, the page resets to the very top, which is annoying to the users, because they have to scroll back down to the point they were at.
If I could capture the current scroll position (in a hidden input) before the page reloads, I could then set it back after it reloads.
The currently accepted answer is incorrect - document.documentElement.scrollTop always returns 0 on Chrome. This is because WebKit uses body for keeping track of scrolling, whereas Firefox and IE use html.
To get the current position, you want:
document.documentElement.scrollTop || document.body.scrollTop
You can set the current position to 1000px down the page like so:
document.documentElement.scrollTop = document.body.scrollTop = 1000;
Or, using jQuery (animate it while you're at it!):
$("html, body").animate({ scrollTop: "1000px" });
You're looking for the document.documentElement.scrollTop property.
Update 2021: browsers inconsistencies with scrollTop seem to have disappeared.
There are some inconsistencies in how browsers expose the current window scrolling coordinates. Google Chrome on Mac and iOS seems to always return 0 when using document.documentElement.scrollTop or jQuery's $(window).scrollTop().
However, it works consistently with:
// horizontal scrolling amount
window.pageXOffset
// vertical scrolling amount
window.pageYOffset
I went with the HTML5 local storage solution... All my links call a function which sets this before changing window.location:
localStorage.topper = document.body.scrollTop;
and each page has this in the body's onLoad:
if(localStorage.topper > 0){
window.scrollTo(0,localStorage.topper);
}
this will give you the px value of scroll from top
document.documentElement.scrollTop
Nowadays it seems like the get is working with: window.scrollX and window.scrollY. This could be an alternative way to solve it.
var stop = true;
addEventListener('drag', (event) => {
if (event.clientY < 150) {
stop = false;
scroll(-1)
}
if (event.clientY > ($(window).height() - 150)) {
stop = false;
scroll(1)
}
if (document.body.getBoundingClientRect().y === 0){
stop = true;
}
if ((window.innerHeight + window.scrollY) >= document.body.scrollHeight) {
stop = true;
}
});
addEventListener('dragend', (event) => {
stop = true;
});
var scroll = function (step) {
var scrollY = $(window).scrollTop();
$(window).scrollTop(scrollY + step);
if (!stop) {
setTimeout(function () { scroll(step) }, 20);
}
}
Now you can also use window.scrollTo({ top: 0, behavior: 'smooth' }); instead of using that jQuery solution above for the animation. Here is the documentation: https://developer.mozilla.org/en-US/docs/Web/API/Window/scrollTo
Related
I have this event:
$(window).scroll(function(e){
console.log(e);
})
I want to know, how much I have scroll value in pixels, because I think, scroll value depends from window size and screen resolution.
Function parameter e does not contains this information.
I can store $(window).scrollTop() after every scroll and calculate difference, but can I do it differently?
The "scroll value" does not depend on the window size or screen resolution. The "scroll value" is simply the number of pixels scrolled.
However, whether you are able to scroll at all, and the amount you can scroll is based on available real estate for the container and the dimensions of the content within the container (in this case the container is document.documentElement, or document.body for older browsers).
You are correct that the scroll event does not contain this information. It does not provide a delta property to indicate the number of pixels scrolled. This is true for the native scroll event and the jQuery scroll event. This seems like it would be a useful feature to have, similar to how mousewheel events provide properties for X and Y delta.
I do not know, and will not speculate upon, why the powers-that-be did not provide a delta property for scroll, but that is out of scope for this question (feel free to post a separate question about this).
The method you are using of storing scrollTop in a variable and comparing it to the current scrollTop is the best (and only) method I have found. However, you can simplify this a bit by extending jQuery to provide a new custom event, per this article: http://learn.jquery.com/events/event-extensions/
Here is an example extension I created that works with window / document scrolling. It is a custom event called scrolldelta that automatically tracks the X and Y delta (as scrollLeftDelta and scrollTopDelta, respectively). I have not tried it with other elements; leaving this as exercise for the reader. This works in currrent versions of Chrome and Firefox. It uses the trick for getting the sum of document.documentElement.scrollTop and document.body.scrollTop to handle the bug where Chrome updates body.scrollTop instead of documentElement.scrollTop (IE and FF update documentElement.scrollTop; see https://code.google.com/p/chromium/issues/detail?id=2891).
JSFiddle demo: http://jsfiddle.net/tew9zxc1/
Runnable Snippet (scroll down and click Run code snippet):
// custom 'scrolldelta' event extends 'scroll' event
jQuery.event.special.scrolldelta = {
delegateType: "scroll",
bindType: "scroll",
handle: function (event) {
var handleObj = event.handleObj;
var targetData = jQuery.data(event.target);
var ret = null;
var elem = event.target;
var isDoc = elem === document;
var oldTop = targetData.top || 0;
var oldLeft = targetData.left || 0;
targetData.top = isDoc ? elem.documentElement.scrollTop + elem.body.scrollTop : elem.scrollTop;
targetData.left = isDoc ? elem.documentElement.scrollLeft + elem.body.scrollLeft : elem.scrollLeft;
event.scrollTopDelta = targetData.top - oldTop;
event.scrollTop = targetData.top;
event.scrollLeftDelta = targetData.left - oldLeft;
event.scrollLeft = targetData.left;
event.type = handleObj.origType;
ret = handleObj.handler.apply(this, arguments);
event.type = handleObj.type;
return ret;
}
};
// bind to custom 'scrolldelta' event
$(window).on('scrolldelta', function (e) {
var top = e.scrollTop;
var topDelta = e.scrollTopDelta;
var left = e.scrollLeft;
var leftDelta = e.scrollLeftDelta;
// do stuff with the above info; for now just display it to user
var feedbackText = 'scrollTop: ' + top.toString() + 'px (' + (topDelta >= 0 ? '+' : '') + topDelta.toString() + 'px), scrollLeft: ' + left.toString() + 'px (' + (leftDelta >= 0 ? '+' : '') + leftDelta.toString() + 'px)';
document.getElementById('feedback').innerHTML = feedbackText;
});
#content {
/* make window tall enough for vertical scroll */
height: 2000px;
/* make window wide enough for horizontal scroll */
width: 2000px;
/* visualization of scrollable content */
background-color: blue;
}
#feedback {
border:2px solid red;
padding: 4px;
color: black;
position: fixed;
top: 0;
height: 20px;
background-color: #fff;
font-family:'Segoe UI', 'Arial';
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id='feedback'>scrollTop: 0px, scrollLeft: 0px</div>
<div id='content'></div>
Note that you may want debounce the event depending on what you are doing. You didn't provide very much context in your question, but if you give a better example of what you are actually using this info for we can provide a better answer. (Please show more of your code, and how you are using the "scroll value").
To detemine how many pixels were scrolled you have to keep in mind that the scroll event gets fired almost every pixel that you move. The way to accomplish it is to save the previous scrolled value and compare that in a timeout. Like this:
var scrollValue = 0;
var scrollTimeout = false
$(window).scroll(function(event){
/* Clear it so the function only triggers when scroll events have stopped firing*/
clearTimeout(scrollTimeout);
/* Set it so it fires after a second, but gets cleared after a new triggered event*/
scrollTimeout = setTimeout(function(){
var scrolled = $(document).scrollTop() - scrollValue;
scrollValue = $(document).scrollTop();
alert("The value scrolled was " + scrolled);
}, 1000);
});
This way you will get the amount of scrolled a second after scrolling (this is adjustable but you have to keep in mind that the smooth scrolling that is so prevalent today has some run-out time and you dont want to trigger before a full stop).
The other way to do this? Yes, possible, with jQuery Mobile
I do not appreciate this solution, because it is necessary to include heavy jQuery mobile. Solution:
var diff, top = 0;
$(document).on("scrollstart",function () {
// event fired when scrolling is started
top = $(window).scrollTop();
});
$(document).on("scrollstop",function () {
// event fired when scrolling is stopped
diff = Math.abs($(window).scrollTop() - top);
});
To reduce the used processing power by adding a timer to a Jquery scroll method is probably not a great idea. The visual effect is indeed quite bad.
The whole web browsing experience could be made much better by hiding the scrolling element just when the scroll begins and making it slide in (at the right position) some time after. The scrolling even can be checked with a delay too.
This solution works great.
$(document).ready(function() {
var element = $('.movable_div'),
originalY = element.offset().top;
element.css('position', 'relative');
$(window).on('scroll', function(event) {
var scrollTop = $(window).scrollTop();
element.hide();
element.stop(false, false).animate({
top: scrollTop < originalY
? 0
: scrollTop - originalY + 35
}, 2000,function(){element.slideDown(500,"swing");});
});
});
Live demo here
I'm working on a transitioning website, and while I want to use the user's scroll attempt as the transition initiator, I don't want there to be a window scroll bar.
Right now, I'm simply detecting that the user scrolls (I've made my window size 1px taller that the user's screen for a scrollbar, although this is what I'm trying to avoid) with jquery's
.scroll(function)
method, and using that to transition my page, but I'd like to detect the user's scroll attempt without having to make my page overflow by a pixel, and thus showing the scrollbar
How can this be done?
Messy patch possibility that I know of:
Positioning the window inside an outer wrapper and hiding the scrollbar in the overflow of the wrapper. This is a patch up job and not a solution. It results in the page content being off-center since not all browsers use the same width for their scrollbars.
Have a look at this question. I used it as a reference to make this fiddle.
Works only in Firefox:
$('html').on ('DOMMouseScroll', function (e) {
var delta = e.originalEvent.detail;
if (delta < 0) {
$('p').text ('You scrolled up');
} else if (delta > 0) {
$('p').text ('You scrolled down');
}
});
Works in Chrome, IE, Opera and Safari:
$('html').on ('mousewheel', function (e) {
var delta = e.originalEvent.wheelDelta;
if (delta < 0) {
$('p').text ('You scrolled down');
} else if (delta > 0) {
$('p').text ('You scrolled up');
}
});
You'd have to bind it on an element that spans your entire browser screen.
The answer from TreeTree can be simplified into one function that supports all browsers. Combine the mousewheel and DOMMouseScroll events since jQuery supports one or more event parameter(s). However, my testing showed on() did not work in the latest Firefox. Use bind() instead. You can also combine the var delta declaration to support all browsers:
$('html').bind('mousewheel DOMMouseScroll', function (e) {
var delta = (e.originalEvent.wheelDelta || -e.originalEvent.detail);
if (delta < 0) {
console.log('You scrolled down');
} else if (delta > 0) {
console.log('You scrolled up');
}
});
The modern solution relies on the wheel event (IE9+)
$('selector').on('wheel', function(event) {
var delta = {
x: event.originalEvent.deltaX,
y: event.originalEvent.deltaY
};
if (delta.x != 0 || delta.y != 0) {
//user scrolled
}
});
I have a bit of text that I want to change when the user scrolls a certain distance. However, when I scroll, the value of document.body.scrollTop remains at 0.
var scroll = document.body.scrollTop;
if (scroll < 50) {
document.write("A");
} else {
document.write("B");
}
When checking the log, the value of scroll never budges from 0, thus the text never switches from A to B when scrolling. Thanks for any help in advance.
EDIT: None of the first three answers seem to work for me. I suppose I should provide some context.
Building my design portfolio site. View the early build here. I'd like to be able to change the word "designer" in the banner to other descriptor words as the user scrolls down the page, but can't seem to be able to listen to the current scroll location.
Why are you placing that script inline within the banner? Why not implement your logic within your existing $(window).scroll(function () { as that event seems to be setting the opacity correctly on scroll.
Just add:
if(scrollTop < 50){
$('#banner h1').text("My name is John. I'm a designer");
} else {
$('#banner h1').text("My name is John. I'm a thinker");
}
Live Demo
if(document.attachEvent){
document.attachEvent('onscroll', scrollEvent);
}else if(document.addEventListener){
document.addEventListener('scroll', scrollEvent, false);
}
function scrollEvent(e){
var scroll = document.body.scrollTop;
var text = null;
if (scroll < 50) {
text = document.createTextNode('A');
} else {
text = document.createTextNode('B');
}
document.body.appendChild(text);
}
Though unrelated to your issue, you should stay away from document.write whenever you can. See Why is document.write considered a "bad practice"? for more detail.
this should do it. "document.documentElement.scrollTop" is an IE variant.
should work cross browsers.
window.onscroll = function() {
var scroll = window.scrollY || document.documentElement.scrollTop;
if (scroll < 50) {
document.write("A");
} else {
document.write("B");
}
}
DEMO FIDDLE
var el = $('.test');
//alert(el.scrollTop());
el.on('scroll', function(){
if(el.scrollTop()>50){
alert(el.scrollTop());
}
});
Try this.
I've been working on a scroll to top function for my website, and that part of it works fine. My problem is however that I have a fixed div that is overlapping my footer when it hits the bottom of the page.
Here is the function that I have working.
$(document).scroll(function (e) {
if (document.body.scrollTop >= 800) {
$('#beamUp').show(1000);
} else {
$('#beamUp').hide(1000);
return false;
}
});
Is there somehow I could detect when I hit that part of the page and stop the div from moving past that.Help is much appreciated!
jsFiddle: http://jsfiddle.net/zazvorniki/RTDpw/
Just get the height of the page, minus the height of the div in question, as well as the footer... make sure the top is never greater than that value... you'll also need an onresize event handler re-evaluate that value.
looking at your jsfiddle... here are my edits
In your scroll listener, I am checking for the position of the page, and adjusting the bottom position of the floater appropriately. I also set the initial display:none, so you don't need to call .hide() in your initial script. In addition, resizing the window has the effect of scrolling for your use, so I changed the listener for both events.
$(document).on('scroll resize', function (e) {
var viewHeight = $(window).height();
var viewTop = $(window).scrollTop();
var footerTop = $("footer").offset().top;
var baseline = (viewHeight + viewTop) - footerTop;
var bu = $("#beamUp").css({bottom: (baseline < 0 ? 0 : baseline) + 'px'});
if (viewTop >= 50) {
bu.show(1000);
} else {
bu.hide(1000);
}
});
I have an HTML document with images in a grid format using <ul><li><img.... The browser window has both vertical & horizontal scrolling.
Question:
When I click on an image <img>, how then do I get the whole document to scroll to a position where the image I just clicked on is top:20px; left:20px ?
I've had a browse on here for similar posts...although I'm quite new to JavaScript, and want to understand how this is achieved for myself.
There's a DOM method called scrollIntoView, which is supported by all major browsers, that will align an element with the top/left of the viewport (or as close as possible).
$("#myImage")[0].scrollIntoView();
On supported browsers, you can provide options:
$("#myImage")[0].scrollIntoView({
behavior: "smooth", // or "auto" or "instant"
block: "start" // or "end"
});
Alternatively, if all the elements have unique IDs, you can just change the hash property of the location object for back/forward button support:
$(document).delegate("img", function (e) {
if (e.target.id)
window.location.hash = e.target.id;
});
After that, just adjust the scrollTop/scrollLeft properties by -20:
document.body.scrollLeft -= 20;
document.body.scrollTop -= 20;
Since you want to know how it works, I'll explain it step-by-step.
First you want to bind a function as the image's click handler:
$('#someImage').click(function () {
// Code to do scrolling happens here
});
That will apply the click handler to an image with id="someImage". If you want to do this to all images, replace '#someImage' with 'img'.
Now for the actual scrolling code:
Get the image offsets (relative to the document):
var offset = $(this).offset(); // Contains .top and .left
Subtract 20 from top and left:
offset.left -= 20;
offset.top -= 20;
Now animate the scroll-top and scroll-left CSS properties of <body> and <html>:
$('html, body').animate({
scrollTop: offset.top,
scrollLeft: offset.left
});
Simplest solution I have seen
var offset = $("#target-element").offset();
$('html, body').animate({
scrollTop: offset.top,
scrollLeft: offset.left
}, 1000);
Tutorial Here
There are methods to scroll element directly into the view, but if you want to scroll to a point relative from an element, you have to do it manually:
Inside the click handler, get the position of the element relative to the document, subtract 20 and use window.scrollTo:
var pos = $(this).offset();
var top = pos.top - 20;
var left = pos.left - 20;
window.scrollTo((left < 0 ? 0 : left), (top < 0 ? 0 : top));
Have a look at the jQuery.scrollTo plugin. Here's a demo.
This plugin has a lot of options that go beyond what native scrollIntoView offers you. For instance, you can set the scrolling to be smooth, and then set a callback for when the scrolling finishes.
You can also have a look at all the JQuery plugins tagged with "scroll".
Here's a quick jQuery plugin to map the built in browser functionality nicely:
$.fn.ensureVisible = function () { $(this).each(function () { $(this)[0].scrollIntoView(); }); };
...
$('.my-elements').ensureVisible();
After trial and error I came up with this function, works with iframe too.
function bringElIntoView(el) {
var elOffset = el.offset();
var $window = $(window);
var windowScrollBottom = $window.scrollTop() + $window.height();
var scrollToPos = -1;
if (elOffset.top < $window.scrollTop()) // element is hidden in the top
scrollToPos = elOffset.top;
else if (elOffset.top + el.height() > windowScrollBottom) // element is hidden in the bottom
scrollToPos = $window.scrollTop() + (elOffset.top + el.height() - windowScrollBottom);
if (scrollToPos !== -1)
$('html, body').animate({ scrollTop: scrollToPos });
}
My UI has a vertical scrolling list of thumbs within a thumbbar
The goal was to make the current thumb right in the center of the thumbbar.
I started from the approved answer, but found that there were a few tweaks to truly center the current thumb. hope this helps someone else.
markup:
<ul id='thumbbar'>
<li id='thumbbar-123'></li>
<li id='thumbbar-124'></li>
<li id='thumbbar-125'></li>
</ul>
jquery:
// scroll the current thumb bar thumb into view
heightbar = $('#thumbbar').height();
heightthumb = $('#thumbbar-' + pageid).height();
offsetbar = $('#thumbbar').scrollTop();
$('#thumbbar').animate({
scrollTop: offsetthumb.top - heightbar / 2 - offsetbar - 20
});
Just a tip. Works on firefox only
Element.scrollIntoView();
Simple 2 steps for scrolling down to end or bottom.
Step1: get the full height of scrollable(conversation) div.
Step2: apply scrollTop on that scrollable(conversation) div using the value
obtained in step1.
var fullHeight = $('#conversation')[0].scrollHeight;
$('#conversation').scrollTop(fullHeight);
Above steps must be applied for every append on the conversation div.
After trying to find a solution that handled every circumstance (options for animating the scroll, padding around the object once it scrolls into view, works even in obscure circumstances such as in an iframe), I finally ended up writing my own solution to this. Since it seems to work when many other solutions failed, I thought I'd share it:
function scrollIntoViewIfNeeded($target, options) {
var options = options ? options : {},
$win = $($target[0].ownerDocument.defaultView), //get the window object of the $target, don't use "window" because the element could possibly be in a different iframe than the one calling the function
$container = options.$container ? options.$container : $win,
padding = options.padding ? options.padding : 20,
elemTop = $target.offset().top,
elemHeight = $target.outerHeight(),
containerTop = $container.scrollTop(),
//Everything past this point is used only to get the container's visible height, which is needed to do this accurately
containerHeight = $container.outerHeight(),
winTop = $win.scrollTop(),
winBot = winTop + $win.height(),
containerVisibleTop = containerTop < winTop ? winTop : containerTop,
containerVisibleBottom = containerTop + containerHeight > winBot ? winBot : containerTop + containerHeight,
containerVisibleHeight = containerVisibleBottom - containerVisibleTop;
if (elemTop < containerTop) {
//scroll up
if (options.instant) {
$container.scrollTop(elemTop - padding);
} else {
$container.animate({scrollTop: elemTop - padding}, options.animationOptions);
}
} else if (elemTop + elemHeight > containerTop + containerVisibleHeight) {
//scroll down
if (options.instant) {
$container.scrollTop(elemTop + elemHeight - containerVisibleHeight + padding);
} else {
$container.animate({scrollTop: elemTop + elemHeight - containerVisibleHeight + padding}, options.animationOptions);
}
}
}
$target is a jQuery object containing the object you wish to scroll into view if needed.
options (optional) can contain the following options passed in an object:
options.$container - a jQuery object pointing to the containing element of $target (in other words, the element in the dom with the scrollbars). Defaults to the window that contains the $target element and is smart enough to select an iframe window. Remember to include the $ in the property name.
options.padding - the padding in pixels to add above or below the object when it is scrolled into view. This way it is not right against the edge of the window. Defaults to 20.
options.instant - if set to true, jQuery animate will not be used and the scroll will instantly pop to the correct location. Defaults to false.
options.animationOptions - any jQuery options you wish to pass to the jQuery animate function (see http://api.jquery.com/animate/). With this, you can change the duration of the animation or have a callback function executed when the scrolling is complete. This only works if options.instant is set to false. If you need to have an instant animation but with a callback, set options.animationOptions.duration = 0 instead of using options.instant = true.