How can I check if a scrollbar is visible? - javascript

Is it possible to check the overflow:auto of a div?
For example:
HTML
<div id="my_div" style="width: 100px; height:100px; overflow:auto;" class="my_class">
* content
</div>
JQUERY
$('.my_class').live('hover', function (event)
{
if (event.type == 'mouseenter')
{
if( ... if scrollbar visible ? ... )
{
alert('true'):
}
else
{
alert('false'):
}
}
});
Sometimes is the content short (no scrollbar) and sometimes long (scrollbar visible).

a little plugin for it.
(function($) {
$.fn.hasScrollBar = function() {
return this.get(0).scrollHeight > this.height();
}
})(jQuery);
use it like this,
$('#my_div1').hasScrollBar(); // returns true if there's a `vertical` scrollbar, false otherwise..
tested working on Firefox, Chrome, IE6,7,8
but not working properly on body tag selector
demo
Edit
I found out that when you have horizontal scrollbar that causes vertical scrollbar to appear, this function does not work....
I found out another solution... use clientHeight
return this.get(0).scrollHeight > this.get(0).clientHeight;

You can do this using a combination of the Element.scrollHeight and Element.clientHeight attributes.
According to MDN:
The Element.scrollHeight read-only attribute is a measurement of the height of an element's content, including content not visible on the screen due to overflow. The scrollHeight value is equal to the minimum clientHeight the element would require in order to fit all the content in the viewpoint without using a vertical scrollbar. It includes the element padding but not its margin.
And:
The Element.clientHeight read-only property returns the inner height of an element in pixels, including padding but not the horizontal scrollbar height, border, or margin.
clientHeight can be calculated as CSS height + CSS padding - height of horizontal scrollbar (if present).
Therefore, the element will display a scrollbar if the scroll height is greater than the client height, so the answer to your question is:
function scrollbarVisible(element) {
return element.scrollHeight > element.clientHeight;
}

Maybe a more simple solution.
if ($(document).height() > $(window).height()) {
// scrollbar
}

I should change a little thing of what Reigel said:
(function($) {
$.fn.hasScrollBar = function() {
return this[0] ? this[0].scrollHeight > this.innerHeight() : false;
}
})(jQuery);
innerHeight counts control's height and its top and bottom paddings

This expands on #Reigel's answer. It will return an answer for horizontal or vertical scrollbars.
(function($) {
$.fn.hasScrollBar = function() {
var e = this.get(0);
return {
vertical: e.scrollHeight > e.clientHeight,
horizontal: e.scrollWidth > e.clientWidth
};
}
})(jQuery);
Example:
element.hasScrollBar() // Returns { vertical: true/false, horizontal: true/false }
element.hasScrollBar().vertical // Returns true/false
element.hasScrollBar().horizontal // Returns true/false

You need element.scrollHeight. Compare it with $(element).height().

I made a new custom :pseudo selector for jQuery to test whether an item has one of the following css properties:
overflow: [scroll|auto]
overflow-x: [scroll|auto]
overflow-y: [scroll|auto]
I wanted to find the closest scrollable parent of another element so I also wrote another little jQuery plugin to find the closest parent with overflow.
This solution probably doesn't perform the best, but it does appear to work. I used it in conjunction with the $.scrollTo plugin. Sometimes I need to know whether an element is inside another scrollable container. In that case I want to scroll the parent scrollable element vs the window.
I probably should have wrapped this up in a single plugin and added the psuedo selector as a part of the plugin, as well as exposing a 'closest' method to find the closest (parent) scrollable container.
Anywho....here it is.
$.isScrollable jQuery plugin:
$.fn.isScrollable = function(){
var elem = $(this);
return (
elem.css('overflow') == 'scroll'
|| elem.css('overflow') == 'auto'
|| elem.css('overflow-x') == 'scroll'
|| elem.css('overflow-x') == 'auto'
|| elem.css('overflow-y') == 'scroll'
|| elem.css('overflow-y') == 'auto'
);
};
$(':scrollable') jQuery pseudo selector:
$.expr[":"].scrollable = function(a) {
var elem = $(a);
return elem.isScrollable();
};
$.scrollableparent() jQuery plugin:
$.fn.scrollableparent = function(){
return $(this).closest(':scrollable') || $(window); //default to $('html') instead?
};
Implementation is pretty simple
//does a specific element have overflow scroll?
var somedivIsScrollable = $(this).isScrollable();
//use :scrollable psuedo selector to find a collection of child scrollable elements
var scrollableChildren = $(this).find(':scrollable');
//use $.scrollableparent to find closest scrollable container
var scrollableparent = $(this).scrollableparent();
UPDATE: I found that Robert Koritnik already came up with a much more powerful :scrollable pseudo selector that will identify the scrollable axes and height of scrollable containers, as a part of his $.scrollintoview() jQuery plugin. scrollintoview plugin
Here is his fancy pseudo selector (props):
$.extend($.expr[":"], {
scrollable: function (element, index, meta, stack) {
var direction = converter[typeof (meta[3]) === "string" && meta[3].toLowerCase()] || converter.both;
var styles = (document.defaultView && document.defaultView.getComputedStyle ? document.defaultView.getComputedStyle(element, null) : element.currentStyle);
var overflow = {
x: scrollValue[styles.overflowX.toLowerCase()] || false,
y: scrollValue[styles.overflowY.toLowerCase()] || false,
isRoot: rootrx.test(element.nodeName)
};
// check if completely unscrollable (exclude HTML element because it's special)
if (!overflow.x && !overflow.y && !overflow.isRoot)
{
return false;
}
var size = {
height: {
scroll: element.scrollHeight,
client: element.clientHeight
},
width: {
scroll: element.scrollWidth,
client: element.clientWidth
},
// check overflow.x/y because iPad (and possibly other tablets) don't dislay scrollbars
scrollableX: function () {
return (overflow.x || overflow.isRoot) && this.width.scroll > this.width.client;
},
scrollableY: function () {
return (overflow.y || overflow.isRoot) && this.height.scroll > this.height.client;
}
};
return direction.y && size.scrollableY() || direction.x && size.scrollableX();
}
});

(scrollWidth/Height - clientWidth/Height) is a good indicator for the presence of a scrollbar, but it will give you a "false positive" answer on many occasions.
if you need to be accurate i would suggest using the following function.
instead of trying to guess if the element is scrollable - you can scroll it...
function isScrollable( el ){
var y1 = el.scrollTop;
el.scrollTop += 1;
var y2 = el.scrollTop;
el.scrollTop -= 1;
var y3 = el.scrollTop;
el.scrollTop = y1;
var x1 = el.scrollLeft;
el.scrollLeft += 1;
var x2 = el.scrollLeft;
el.scrollLeft -= 1;
var x3 = el.scrollLeft;
el.scrollLeft = x1;
return {
horizontallyScrollable: x1 !== x2 || x2 !== x3,
verticallyScrollable: y1 !== y2 || y2 !== y3
}
}
function check( id ){
alert( JSON.stringify( isScrollable( document.getElementById( id ))));
}
#outer1, #outer2, #outer3 {
background-color: pink;
overflow: auto;
float: left;
}
#inner {
width: 150px;
height: 150px;
}
button { margin: 2em 0 0 1em; }
<div id="outer1" style="width: 100px; height: 100px;">
<div id="inner">
<button onclick="check('outer1')">check if<br>scrollable</button>
</div>
</div>
<div id="outer2" style="width: 200px; height: 100px;">
<div id="inner">
<button onclick="check('outer2')">check if<br>scrollable</button>
</div>
</div>
<div id="outer3" style="width: 100px; height: 180px;">
<div id="inner">
<button onclick="check('outer3')">check if<br>scrollable</button>
</div>
</div>

Ugh everyone's answers on here are incomplete, and lets stop using jquery in SO answers already please. Check jquery's documentation if you want info on jquery.
Here's a generalized pure-javascript function for testing whether or not an element has scrollbars in a complete way:
// dimension - Either 'y' or 'x'
// computedStyles - (Optional) Pass in the domNodes computed styles if you already have it (since I hear its somewhat expensive)
function hasScrollBars(domNode, dimension, computedStyles) {
dimension = dimension.toUpperCase()
if(dimension === 'Y') {
var length = 'Height'
} else {
var length = 'Width'
}
var scrollLength = 'scroll'+length
var clientLength = 'client'+length
var overflowDimension = 'overflow'+dimension
var hasVScroll = domNode[scrollLength] > domNode[clientLength]
// Check the overflow and overflowY properties for "auto" and "visible" values
var cStyle = computedStyles || getComputedStyle(domNode)
return hasVScroll && (cStyle[overflowDimension] == "visible"
|| cStyle[overflowDimension] == "auto"
)
|| cStyle[overflowDimension] == "scroll"
}

The first solution above works only in IE
The second solution above works only in FF
This combination of both functions works in both browsers:
//Firefox Only!!
if ($(document).height() > $(window).height()) {
// has scrollbar
$("#mtc").addClass("AdjustOverflowWidth");
alert('scrollbar present - Firefox');
} else {
$("#mtc").removeClass("AdjustOverflowWidth");
}
//Internet Explorer Only!!
(function($) {
$.fn.hasScrollBar = function() {
return this.get(0).scrollHeight > this.innerHeight();
}
})(jQuery);
if ($('#monitorWidth1').hasScrollBar()) {
// has scrollbar
$("#mtc").addClass("AdjustOverflowWidth");
alert('scrollbar present - Internet Exploder');
} else {
$("#mtc").removeClass("AdjustOverflowWidth");
}​
Wrap in a document ready
monitorWidth1 : the div where the overflow is set to auto
mtc : a container div inside monitorWidth1
AdjustOverflowWidth : a css class applied to the #mtc div when the Scrollbar is active
*Use the alert to test cross browser, and then comment out for final production code.
HTH

I'm going to extend on this even further for those poor souls who, like me, use one of the modern js frameworks and not JQuery and have been wholly abandoned by the people of this thread :
this was written in Angular 6 but if you write React 16, Vue 2, Polymer, Ionic, React-Native, you'll know what to do to adapt it. And it's the whole component so it should be easy.
import {ElementRef, AfterViewInit} from '#angular/core';
#Component({
selector: 'app',
templateUrl: './app.html',
styleUrls: ['./app.scss']
})
export class App implements AfterViewInit {
scrollAmount;
constructor(
private fb: FormBuilder,
private element: ElementRef
) {}
ngAfterViewInit(){
this.scrollAmount = this.element.nativeElement.querySelector('.elem-list');
this.scrollAmount.addEventListener('wheel', e => { //you can put () instead of e
// but e is usefull if you require the deltaY amount.
if(this.scrollAmount.scrollHeight > this.scrollAmount.offsetHeight){
// there is a scroll bar, do something!
}else{
// there is NO scroll bar, do something!
}
});
}
}
in the html there would be a div with class "elem-list" which is stylized in the css or scss to have a height and an overflow value that isn't hidden. (so auto or sroll )
I trigger this eval upon a scroll event because my end goal was to have "automatic focus scrolls" which decide whether they are scrolling the whole set of components horizontally if said components have no vertical scroll available and otherwise only scroll the innards of one of the components vertically.
but you can place the eval elsewhere to have it be triggered by something else.
the important thing to remember here, is you're never Forced back into using JQuery, there's always a way to access the same functionalities it has without using it.

The solutions provided above will work in the most cases, but checking the scrollHeight and overflow is sometimes not enough and can fail for body and html elements as seen here:
https://codepen.io/anon/pen/EvzXZw
1. Solution - Check if the element is scrollable:
function isScrollableY (element) {
return !!(element.scrollTop || (++element.scrollTop && element.scrollTop--));
}
Note: elements with overflow: hidden are also treated as scrollable (more info), so you might add a condition against that too if needed:
function isScrollableY (element) {
let style = window.getComputedStyle(element);
return !!(element.scrollTop || (++element.scrollTop && element.scrollTop--))
&& style["overflow"] !== "hidden" && style["overflow-y"] !== "hidden";
}
As far as I know this method only fails if the element has scroll-behavior: smooth.
Explanation: The trick is, that the attempt of scrolling down and reverting it won't be rendered by the browser. The topmost function can also be written like the following:
function isScrollableY (element) {
// if scrollTop is not 0 / larger than 0, then the element is scrolled and therefore must be scrollable
// -> true
if (element.scrollTop === 0) {
// if the element is zero it may be scrollable
// -> try scrolling about 1 pixel
element.scrollTop++;
// if the element is zero then scrolling did not succeed and therefore it is not scrollable
// -> false
if (element.scrollTop === 0) return false;
// else the element is scrollable; reset the scrollTop property
// -> true
element.scrollTop--;
}
return true;
}
2. Solution - Do all the necessary checks:
function isScrollableY (element) {
const style = window.getComputedStyle(element);
if (element.scrollHeight > element.clientHeight &&
style["overflow"] !== "hidden" && style["overflow-y"] !== "hidden" &&
style["overflow"] !== "clip" && style["overflow-y"] !== "clip"
) {
if (element === document.scrollingElement) return true;
else if (style["overflow"] !== "visible" && style["overflow-y"] !== "visible") {
// special check for body element (https://drafts.csswg.org/cssom-view/#potentially-scrollable)
if (element === document.body) {
const parentStyle = window.getComputedStyle(element.parentElement);
if (parentStyle["overflow"] !== "visible" && parentStyle["overflow-y"] !== "visible" &&
parentStyle["overflow"] !== "clip" && parentStyle["overflow-y"] !== "clip"
) {
return true;
}
}
else return true;
}
}
return false;
}

Here's an improved version of Evan's answer which seems to properly account for overflow logic.
function element_scrollbars(node) {
var element = $(node);
var overflow_x = element.css("overflow-x");
var overflow_y = element.css("overflow-y");
var overflow = element.css("overflow");
if (overflow_x == "undefined") overflow_x == "";
if (overflow_y == "undefined") overflow_y == "";
if (overflow == "undefined") overflow == "";
if (overflow_x == "") overflow_x = overflow;
if (overflow_y == "") overflow_y = overflow;
var scrollbar_vertical = (
(overflow_y == "scroll")
|| (
(
(overflow_y == "hidden")
|| (overflow_y == "visible")
)
&& (
(node.scrollHeight > node.clientHeight)
)
)
);
var scrollbar_horizontal = (
(overflow_x == "scroll")
|| (
(
(overflow_x == "hidden")
|| (overflow_x == "visible")
)
&& (
(node.scrollWidth > node.clientWidth)
)
)
);
return {
vertical: scrollbar_vertical,
horizontal: scrollbar_horizontal
};
}

Most of the answers presented got me close to where I needed to be, but not quite there.
We basically wanted to assess if the scroll bars -would- be visible in a normal situation, by that definition meaning that the size of the body element is larger than the view port. This was not a presented solution, which is why I am submitting it.
Hopefully it helps someone!
(function($) {
$.fn.hasScrollBar = function() {
return this.get(0).scrollHeight > $(window).height();
}
})(jQuery);
Essentially, we have the hasScrollbar function, but returning if the requested element is larger than the view port. For view port size, we just used $(window).height(). A quick compare of that against the element size, yields the correct results and desirable behavior.

Here's my improvement: added parseInt. for some weird reason it didn't work without it.
// usage: jQuery('#my_div1').hasVerticalScrollBar();
// Credit: http://stackoverflow.com/questions/4814398/how-can-i-check-if-a-scrollbar-is-visible
(function($) {
$.fn.hasVerticalScrollBar = function() {
return this.get(0) ? parseInt( this.get(0).scrollHeight ) > parseInt( this.innerHeight() ) : false;
};
})(jQuery);

Works on Chrome, Edge, Firefox and Opera, at least in the newer versions.
Using JQuery...
Setup this function to fix the footer:
function fixFooterCaller()
{
const body = $('body');
const footer = $('body footer');
return function ()
{
// If the scroll bar is visible
if ($(document).height() > $(window).height())
{
// Reset
footer.css('position', 'inherit');
// Erase the padding added in the above code
body.css('padding-bottom', '0');
}
// If the scrollbar is NOT visible
else
{
// Make it fixed at the bottom
footer.css('position', 'fixed');
// And put a padding to the body as the size of the footer
// This makes the footer do not cover the content and when
// it does, this event fix it
body.css('padding-bottom', footer.outerHeight());
}
}
}
It returns a function. Made this way just to set the body and footer once.
And then, set this when the document is ready.
$(document).ready(function ()
{
const fixFooter = fixFooterCaller();
// Put in a timeout call instead of just call the fixFooter function
// to prevent the page elements needed don't be ready at this time
setTimeout(fixFooter, 0);
// The function must be called every time the window is resized
$(window).resize(fixFooter);
});
Add this to your footer css:
footer {
bottom: 0;
}

Find a parent of current element that has vertical scrolling or body.
$.fn.scrollableParent = function() {
var $parents = this.parents();
var $scrollable = $parents.filter(function(idx) {
return this.scrollHeight > this.offsetHeight && this.offsetWidth !== this.clientWidth;
}).first();
if ($scrollable.length === 0) {
$scrollable = $('html, body');
}
return $scrollable;
};
It may be used to autoscroll to current element via:
var $scrollable = $elem.scrollableParent();
$scrollable.scrollTop($elem.position().top);

A No Framework JavaScript Approach, checks for both vertical and horizontal
/*
* hasScrollBars
*
* Checks to see if an element has scrollbars
*
* #returns {object}
*/
Element.prototype.hasScrollBars = function() {
return {"vertical": this.scrollHeight > this.style.height, "horizontal": this.scrollWidth > this.style.width};
}
Use it like this
if(document.getElementsByTagName("body")[0].hasScrollBars().vertical){
alert("vertical");
}
if(document.getElementsByTagName("body")[0].hasScrollBars().horizontal){
alert("horizontal");
}

There's two area sizes to consider, the window and the html. If the html width, for example, is greater than window width then a scroll bar may be present on the user interface. So it's a matter of reading the window proportions and the html proportions and doing the basic math.
As for displaying an arrow overlaid atop the page, that's done with a simple classlist toggle, e.g. .hidden{display:none}
Here's a crossbrowser method for getting these proportions. (credit W3 Schools)
|| document.body.clientWidth;
var h = window.innerHeight || document.documentElement.clientHeight ||
document.body.clientHeight; ```

I had the problem, that I needed to check, if the scrollbar is visible on the whole screen (body) or not. Chrome has the ability to hide the scrollbar despite the fact that there is an overflow happening, hence the body is scrollable.
Therefore the solutions above did not work for me. I now check, if there is a scrollbar the following way:
const isScrollbarPresent = () => {
const beforeScrollbarHidden = document.body.clientWidth;
const overflowState = document.body?.style.overflow;
document.body.style.overflow = 'hidden';
const afterScrollbarHidden = document.body.clientWidth;
document.body.style.overflow = overflowState;
return beforeScrollbarHidden !== afterScrollbarHidden;
};
I get the width of the body, with or without the scrollbar and save the current overflow state of the body. Then I hide the scrollbar. If there was a scrollbar, the width of the body is now bigger. If not, the width is the same. After that I revert the overflow state.

Another easy answer is the following:
export const isScrollbarPresent = (element?: HTMLElement) => {
const testedElement = element ?? document.body;
return testedElement.scrollHeight > testedElement.clientHeight; }
I check if the scrollHeight of the element is bigger then the clientHeight. The scrollHeight returns the absolute height of an element including all elements, that are not visible. The clientHeight returns the visible height on the screen.

Related

How to prevent hard jumping and what is alternative to position: sticky?

Two questions:
Focus on the part of 'Get early access' bar. It is positioned with position:relative and I want to have it sticky once you move to the 2nd section. I've tried to add helper with the same height in order to get smooth transition when I change the .class to fixed. But not working.
This with helper in previous websites helped me but now it doesn't work and it really bothers me.
What would be alternative to position sticky which works in all browsers? In this particular case, how needs jquery to look like?
Thanks in advance.
/**
* Zirelco
* Custom JS functions
*/
jQuery(document).ready(function ( $ ) {
var mn = $("#sticky-wrapper");
mns = "nav--scrolled";
hdr = $("#top-wrapper-v1").height();
$(window).scroll(function() {
if( $(this).scrollTop() > hdr ) {
mn.addClass(mns);
} else {
mn.removeClass(mns);
}
});
$('.cookies .btn').on('click', function() {
if ($('.cookies').css('opacity') == 0) {
$('.cookies').css('opacity', 1);
}
else {
$('.cookies').addClass('none');
}
});
});
Edit V3
Try this Code instead of yours:
(function(selector) {
selector = selector || '#sticky-wrapper';
var stickyWrapper = document.querySelector(selector)
var stickyTrigger = document.createElement('div')
stickyTrigger.classList.add('sticky-trigger')
stickyWrapper.parentElement.insertBefore(stickyTrigger, stickyWrapper)
var listener = function (e) {
if (stickyTrigger.getBoundingClientRect().top < 0) {
stickyWrapper.classList.add('sticky');
} else {
stickyWrapper.classList.remove('sticky');
}
}
var onScroll = document.addEventListener('scroll', listener);
}('#sticky-wrapper'))
What this does is:
create a .sticky-trigger element
insert this right before #sticky-wrapper
watch for scroll event of document
check the top property of getBoundingClientRect of the .sticky-trigger element
toggle the sticky class of #sticky-wrapper depending on the sign (positive or negative) of that top value
You don't have to change your HTML output at all
Old V1
You use the height of the #top-wrapper-v1 <section> as trigger for the class toggle. But you totally forget the to calc the <header> height as well.
To prevent such mistakes just go for the top edge of the '#sticky-wrapper' as a trigger
// $(window).scroll(function(e) {
// if( $(this).scrollTop() > mn.offset().top ) {
// mn.addClass('sticky');
// } else {
// mn.removeClass('sticky');
// }
//});
Old V2
Because of the comment of the asker, this is an improved way of doing it.
In the previous example, the measurement of the offset().top of #sticky-wrapper is immediately set to 0 caused by position: fixed. In order to break this issue, we wrap the #sticky-wrapper in a trigger element, measure the offset().top of that element as trigger. This trigger element will remain in the document flow and will not be fixed
HTML
<!--
<section id="sticky-trigger">
<section id="sticky-wrapper" class="">
<div class="container" style="position: fixed;top: 0;">
Other content
</div>
</section>
</section>
-->
JavaScript
// var trigger = document.querySelector('#sticky-trigger')
// $(window).scroll(function(e) {
//
// if( $(this).scrollTop() > trigger.offset().top ) {
// mn.addClass('sticky');
// } else {
// mn.removeClass('sticky');
// }
// });

Run function() if appear in viewport ? jquery-viewport-checker

I use anime-js for create an animation. But, It is far in the page. I would like to launch my animation function when the section in which the item to be animated appears on the screen.
I tried a plugin that I like to use (jquery viewportchecker) but it does not seem to do that.
Can you help me ?
Thank you
I found a solution. The problem with your method is that the function repeats itself to infinity.
I create a little function for check if element is visible. With that, no plugin needed.
function checkVisible( elm, evale ) {
var evale;
evale = evale || "object visible";
var viewportHeight = $(window).height(), // Viewport Height
scrolltop = $(window).scrollTop(), // Scroll Top
y = $(elm).offset().top,
elementHeight = $(elm).height();
if (evale == "object visible") return ((y < (viewportHeight + scrolltop)) && (y > (scrolltop - elementHeight)));
if (evale == "above") return ((y < (viewportHeight + scrolltop)));
}
I also created a variable var counter = 0;. And as soon as the function is called, I increment by 1.
$(window).on('scroll',function() {
if (counter == 0){
if (checkVisible($('.frontend'))) {
// Your function here
}
}
}
At the first time the function will be called, counter will be 1, and thus, the function will not repeat. Thank you for your help !
jQuery.appear
This plugin implements custom appear/disappear events which are fired when an element became visible/invisible in the browser viewport.
https://github.com/morr/jquery.appear
$('someselector').on('appear', function(event, $all_appeared_elements) {
// this element is now inside browser viewport
});
$('someselector').on('disappear', function(event, $all_disappeared_elements) {
// this element is now outside browser viewport
});
Also this plugin provides custom jQuery filter for manual checking element appearance.
$('someselector').is(':appeared')
Have you tried using JQuery's on load method?
Something like
$(document).on('load', '.exampleClass', function() { //do stuff } )

How do I code JQuery so that when I scroll to a certain element, Nav bar appears at top, when I scroll back up past that element, nav bar disappears

I have a div called #menu which I want to display when I scroll past the element #section3, if I scroll up past that element again, I want #menu to disappear
How would I code this?
Maybe something like this?
scrolled = "no"
$(window).scroll(function(){
scr = $("body").scrollTop();
if (scr > 100 && scrolled == "no"){
$("#menu").css({"display:block"})
displayed = "yes"
}
if (displayed == "yes" && scrolled = "yes"){
$("#menu").css({"display:none"})
}
});
The above assumes that #section3 is 100 pixels down the page. If you do not know where its going to be on the page then you could use the method outlined here:
Trigger event when user scroll to specific element - with jQuery
With jQuery you can get the scroll position with $("body").scrollTop();.
Expanding on what #Ned Hulton said, I recommend comparing the scroll position to the top of a "container element" (or 'row') in your page like this:
if ($('body').scrollTop() > $('#someRow').offset().top){
//do something
}
That way you can account for your container appearing at a variable distance down the page (which will come in handy for mobile browsing or cases where your text wraps to additional lines)
I just whipped this up in jsfiddle
https://jsfiddle.net/rb56j0yu/
it uses jQuery, and checks the scroll position against the target div. Css sets the menu as position: fixed, and defaults to hidden.
$(window).scroll(function(){
var yPos = $("body").scrollTop();
var yCheck = $("#c3").position().top;
if (yPos > yCheck && !$("#menu").is(":visible"))
{
$("#menu").show();
}
if (yPos <= yCheck && $("#menu").is(":visible"))
{
$("#menu").hide();
}
});
First, get your #section3 top offset and height. Which will be used as the threshold whether #section3 is actually on the window screen.
var top = $('#section3').offset().top;
var bot = topOffset + $('#section3').height();
Then, detect it on your scroll event.
$(window).on('scroll', function () {
var scrollTop = $(window).scrollTop();
if (scrollTop >= top && scrollTop <= bot) {
// #section3 is within the screen.
$('#menu').show();
}
else {
// #section3 is out of screen.
$('#menu').hide();
}
});
This is a common use case, I wrote following code:
// what does "Auto Header" mean, goto https://www.yahoo.com/
// scroll down and you will see the purple part auto fixed to top,
// while when scroll up, it restores and does not be fixed.
// 1. multiple auto header elements handled
// 2. dynamically create/remove elements issue handled
// 3. no unnecessary dom operation, high performance
// usage: just add 'class="auto-header"' to any element you want to auto header
// suggest set each auto-header element specific width and height
// do not guarantee it works when resize or scroll left/right
$(document).ready(function() {
var rawTops = [],
rawLefts = [],
rawStyles = [],
$locations = [], // record next sibling so that element easily find where to restore
fixed = []; // mark whether this element is fixed
$(".auto-header").each(function() {
var $this = $(this),
offset = $this.offset();
rawTops.push(offset.top);
rawLefts.push(offset.left);
rawStyles.push($this.attr("style"));
$locations.push($this.siblings().eq($this.index()));
fixed.push(false);
});
$(window).on("scroll", function() {
$(".auto-header").each(function(i, e) {
if(!fixed[i] && $(window).scrollTop() > rawTops[i]) {
var $te = $(this).clone(true);
$(this).remove();
$locations[i].before($te);
$te.css({
"position": "fixed",
"top": 0,
"left": rawLefts[i],
"z-index": 100
});
fixed[i] = true;
} else if(fixed[i] && $(window).scrollTop() < rawTops[i]) {
$(this).removeAttr("style").attr("style", rawStyles[i]);
fixed[i] = false;
}
});
});
});

How to find out which element is causing a scrollbar

I have a certain question which goes into kind of debugging. I want you to ask, how I could find out which element of the whole markup is causing a scrollbar. Any kind of method would be fine.
I thought about searching for overflow in developer tools, but this doesn't really help me.
Does anyone know how I could solve this?
You will want to check a few things. First, that an element has an overflow that would produce a scrollbar: overflow: scroll forces them and overflow: auto will display them if necessary. In the case that the overflows are auto, you can then check it's scroll height against it's actual height.
function isScroller(el) {
var isScrollableWidth, isScollableHeight, elStyle;
elStyle = window.getComputedStyle(el, null); // Note: IE9+
if (elStyle.overflow === 'scroll' ||
elStyle.overflowX === 'scroll' ||
elStyle.overflowY === 'scroll') {
return true;
}
if (elStyle.overflow === 'auto' ||
elStyle.overflowX === 'auto' ||
elStyle.overflowY === 'auto') {
if (el.scrollHeight > el.clientHeight) {
return true;
}
if (el.scrollWidth > el.clientWidth) {
return true;
}
}
return false;
}
var els = document.querySelectorAll('body *');
for (var i = 0, el; el = els[i]; i++) {
if (isScroller(el)) {
console.log(el);
}
}
You can see it here (open your console): http://jsfiddle.net/rgthree/zfyhby1j/
Note, that some touch devices may not produce an actual "scrollbar" except when scrolling. This won't detect that but, rather, that the element is capable of scrolling.

javascript: detect scroll end

I have a div layer with overflow set to scroll.
When scrolled to the bottom of the div, I wanna run a function.
The accepted answer was fundamentally flawed, it has since been deleted. The correct answer is:
function scrolled(e) {
if (myDiv.offsetHeight + myDiv.scrollTop >= myDiv.scrollHeight) {
scrolledToBottom(e);
}
}
Tested this in Firefox, Chrome and Opera. It works.
I could not get either of the above answers to work so here is a third option that works for me! (This is used with jQuery)
if (($(window).innerHeight() + $(window).scrollTop()) >= $("body").height()) {
//do stuff
}
Hope this helps anyone!
if ((window.innerHeight + window.scrollY) >= document.body.offsetHeight)
{
//your code here
}
I too searched it and even after checking all comments here and more,
this is the solution to check if reached the bottom or not.
OK Here is a Good And Proper Solution
You have a Div call with an id="myDiv"
so the function goes.
function GetScrollerEndPoint()
{
var scrollHeight = $("#myDiv").prop('scrollHeight');
var divHeight = $("#myDiv").height();
var scrollerEndPoint = scrollHeight - divHeight;
var divScrollerTop = $("#myDiv").scrollTop();
if(divScrollerTop === scrollerEndPoint)
{
//Your Code
//The Div scroller has reached the bottom
}
}
This worked for me:
$(window).scroll(function() {
buffer = 40 // # of pixels from bottom of scroll to fire your function. Can be 0
if ($(".myDiv").prop('scrollHeight') - $(".myDiv").scrollTop() <= $(".myDiv").height() + buffer ) {
doThing();
}
});
Must use jQuery 1.6 or higher
I found an alternative that works.
None of these answers worked for me (currently testing in FireFox 22.0), and after a lot of research I found, what seems to be, a much cleaner and straight forward solution.
Implemented solution:
function IsScrollbarAtBottom() {
var documentHeight = $(document).height();
var scrollDifference = $(window).height() + $(window).scrollTop();
return (documentHeight == scrollDifference);
}
Resource: http://jquery.10927.n7.nabble.com/How-can-we-find-out-scrollbar-position-has-reached-at-the-bottom-in-js-td145336.html
Regards
I created a event based solution based on Bjorn Tipling's answer:
(function(doc){
'use strict';
window.onscroll = function (event) {
if (isEndOfElement(doc.body)){
sendNewEvent('end-of-page-reached');
}
};
function isEndOfElement(element){
//visible height + pixel scrolled = total height
return element.offsetHeight + element.scrollTop >= element.scrollHeight;
}
function sendNewEvent(eventName){
var event = doc.createEvent('Event');
event.initEvent(eventName, true, true);
doc.dispatchEvent(event);
}
}(document));
And you use the event like this:
document.addEventListener('end-of-page-reached', function(){
console.log('you reached the end of the page');
});
BTW: you need to add this CSS for javascript to know how long the page is
html, body {
height: 100%;
}
Demo: http://plnkr.co/edit/CCokKfB16iWIMddtWjPC?p=preview
This will actually be the correct answer:
function scrolled(event) {
const container = event.target.body
const {clientHeight, scrollHeight, scrollY: scrollTop} = container
if (clientHeight + scrollY >= scrollHeight) {
scrolledToBottom(event);
}
}
The reason for using the event is up-to-date data, if you'll use a direct reference to the div you'll get outdated scrollY and will fail to detect the position correctly.
additional way is to wrap it in a setTimeout and wait till the data updates.
Take a look at this example: MDN Element.scrollHeight
I recommend that check out this example: stackoverflow.com/a/24815216... which implements a cross-browser handling for the scroll action.
You may use the following snippet:
//attaches the "scroll" event
$(window).scroll(function (e) {
var target = e.currentTarget,
scrollTop = target.scrollTop || window.pageYOffset,
scrollHeight = target.scrollHeight || document.body.scrollHeight;
if (scrollHeight - scrollTop === $(target).innerHeight()) {
console.log("► End of scroll");
}
});
Since innerHeight doesn't work in some old IE versions, clientHeight can be used:
$(window).scroll(function (e){
var body = document.body;
//alert (body.clientHeight);
var scrollTop = this.pageYOffset || body.scrollTop;
if (body.scrollHeight - scrollTop === parseFloat(body.clientHeight)) {
loadMoreNews();
}
});
To do the same in React/JSX, here is the snippet.
export const scrolledToEnd = event => {
const container = event.target;
if (container.offsetHeight + container.scrollTop >= container.scrollHeight) {
return true;
}
return false;
};
And in your component add
<Component onScroll={scrolledToEnd}>
There is experimental onscrollend event https://developer.mozilla.org/en-US/docs/Web/API/Document/scrollend_event
For now works only in firefox 109+, if other browsers catch up will be very nice.
Have polyfill for that https://github.com/argyleink/scrollyfills
Use like
import "scrollyfills";
...
scrollContainer.addEventListener(
"scrollend",
(ev) => { console.log('scroll END') }
);
I found this methode to get the end of the scroll :
let TheBody = document.getElementsByTagName("body"); // I choose the "body" element for my exemple
function OnScrolling(){ // put this on a scrolling EVENT
let ScrollEnd = TheBody[0].scrollHeight - window.innerHeight; // this is the scroll end Pixel
if (ScrollEnd.toFixed() == window.scrollY.toFixed()){
//do stuff
}
}
Okay now for your DIV or any other element that have a scrolling I found this method on JavaScript :
let D = document.getElementById("D1"); // I gave "D1" as id to my div
// this one is to calculate the scroll end Pixels
let Calc = D.scrollHeight - D.clientHeight;
function ScrollingInD1() {
//this one is to calculate the scrolling percent while going through the <div> it can help for "Responsivity"
let percent = (D.scrollTop * 100) / Calc;
if (D.scrollTop == Calc) {
// do Stuffs
}
}

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