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How to determine the real visibility of an element? [duplicate]

This question already has answers here:
Check if element is visible in DOM
(27 answers)
Closed 6 years ago.
In JavaScript, how would you check if an element is actually visible?
I don't just mean checking the visibility and display attributes. I mean, checking that the element is not
visibility: hidden or display: none
underneath another element
scrolled off the edge of the screen
For technical reasons I can't include any scripts. I can however use Prototype as it is on the page already.

For the point 2.
I see that no one has suggested to use document.elementFromPoint(x,y), to me it is the fastest way to test if an element is nested or hidden by another. You can pass the offsets of the targetted element to the function.
Here's PPK test page on elementFromPoint.
From MDN's documentation:
The elementFromPoint() method—available on both the Document and ShadowRoot objects—returns the topmost Element at the specified coordinates (relative to the viewport).

I don't know how much of this is supported in older or not-so-modern browsers, but I'm using something like this (without the neeed for any libraries):
function visible(element) {
if (element.offsetWidth === 0 || element.offsetHeight === 0) return false;
var height = document.documentElement.clientHeight,
rects = element.getClientRects(),
on_top = function(r) {
var x = (r.left + r.right)/2, y = (r.top + r.bottom)/2;
return document.elementFromPoint(x, y) === element;
};
for (var i = 0, l = rects.length; i < l; i++) {
var r = rects[i],
in_viewport = r.top > 0 ? r.top <= height : (r.bottom > 0 && r.bottom <= height);
if (in_viewport && on_top(r)) return true;
}
return false;
}
It checks that the element has an area > 0 and then it checks if any part of the element is within the viewport and that it is not hidden "under" another element (actually I only check on a single point in the center of the element, so it's not 100% assured -- but you could just modify the script to itterate over all the points of the element, if you really need to...).
Update
Modified on_top function that check every pixel:
on_top = function(r) {
for (var x = Math.floor(r.left), x_max = Math.ceil(r.right); x <= x_max; x++)
for (var y = Math.floor(r.top), y_max = Math.ceil(r.bottom); y <= y_max; y++) {
if (document.elementFromPoint(x, y) === element) return true;
}
return false;
};
Don't know about the performance :)

As jkl pointed out, checking the element's visibility or display is not enough. You do have to check its ancestors. Selenium does this when it verifies visibility on an element.
Check out the method Selenium.prototype.isVisible in the selenium-api.js file.
http://svn.openqa.org/svn/selenium-on-rails/selenium-on-rails/selenium-core/scripts/selenium-api.js

Interesting question.
This would be my approach.
At first check that element.style.visibility !== 'hidden' && element.style.display !== 'none'
Then test with document.elementFromPoint(element.offsetLeft, element.offsetTop) if the returned element is the element I expect, this is tricky to detect if an element is overlapping another completely.
Finally test if offsetTop and offsetLeft are located in the viewport taking scroll offsets into account.
Hope it helps.

This is what I have so far. It covers both 1 and 3. I'm however still struggling with 2 since I'm not that familiar with Prototype (I'm more a jQuery type of guy).
function isVisible( elem ) {
var $elem = $(elem);
// First check if elem is hidden through css as this is not very costly:
if ($elem.getStyle('display') == 'none' || $elem.getStyle('visibility') == 'hidden' ) {
//elem is set through CSS stylesheet or inline to invisible
return false;
}
//Now check for the elem being outside of the viewport
var $elemOffset = $elem.viewportOffset();
if ($elemOffset.left < 0 || $elemOffset.top < 0) {
//elem is left of or above viewport
return false;
}
var vp = document.viewport.getDimensions();
if ($elemOffset.left > vp.width || $elemOffset.top > vp.height) {
//elem is below or right of vp
return false;
}
//Now check for elements positioned on top:
//TODO: Build check for this using Prototype...
//Neither of these was true, so the elem was visible:
return true;
}

/**
* Checks display and visibility of elements and it's parents
* #param DomElement el
* #param boolean isDeep Watch parents? Default is true
* #return {Boolean}
*
* #author Oleksandr Knyga <oleksandrknyga#gmail.com>
*/
function isVisible(el, isDeep) {
var elIsVisible = true;
if("undefined" === typeof isDeep) {
isDeep = true;
}
elIsVisible = elIsVisible && el.offsetWidth > 0 && el.offsetHeight > 0;
if(isDeep && elIsVisible) {
while('BODY' != el.tagName && elIsVisible) {
elIsVisible = elIsVisible && 'hidden' != window.getComputedStyle(el).visibility;
el = el.parentElement;
}
}
return elIsVisible;
}

You can use the clientHeight or clientWidth properties
function isViewable(element){
return (element.clientHeight > 0);
}

Prototype's Element library is one of the most powerful query libraries in terms of the methods. I recommend you to check out the API.
A few hints:
Checking visibility can be a pain, but you can use the Element.getStyle() method and Element.visible() methods combined into a custom function. With getStyle() you can check the actual computed style.
I don't know exactly what you mean by "underneath" :) If you meant by it has a specific ancestor, for example, a wrapper div, you can use Element.up(cssRule):
var child = $("myparagraph");
if(!child.up("mywrapper")){
// I lost my mom!
}
else {
// I found my mom!
}
If you want to check the siblings of the child element you can do that too:
var child = $("myparagraph");
if(!child.previous("mywrapper")){
// I lost my bro!
}
else {
// I found my bro!
}
Again, Element lib can help you if I understand correctly what you mean :) You can check the actual dimensions of the viewport and the offset of your element so you can calculate if your element is "off screen".
Good luck!
I pasted a test case for prototypejs at http://gist.github.com/117125. It seems in your case we simply cannot trust in getStyle() at all. For maximizing the reliability of the isMyElementReallyVisible function you should combine the following:
Checking the computed style (dojo has a nice implementation that you can borrow)
Checking the viewportoffset (prototype native method)
Checking the z-index for the "beneath" problem (under Internet Explorer it may be buggy)

One way to do it is:
isVisible(elm) {
while(elm.tagName != 'BODY') {
if(!$(elm).visible()) return false;
elm = elm.parentNode;
}
return true;
}
Credits: https://github.com/atetlaw/Really-Easy-Field-Validation/blob/master/validation.js#L178

Try element.getBoundingClientRect().
It will return an object with properties
bottom
top
right
left
width -- browser dependent
height -- browser dependent
Check that the width and height of the element's BoundingClientRect are not zero which is the value of hidden or non-visible elements. If the values are greater than zero the element should be visible in the body. Then check if the bottom property is less than screen.height which would imply that the element is withing the viewport. (Technically you would also have to account for the top of the browser window including the searchbar, buttons, etc.)

Catch mouse-drag and viewport events (onmouseup, onresize, onscroll).
When a drag ends do a comparison of the dragged item boundary with all "elements of interest" (ie, elements with class "dont_hide" or an array of ids). Do the same with window.onscroll and window.onresize. Mark any elements hidden with a special attribute or classname or simply perform whatever action you want then and there.
The hidden tests are pretty easy. For "totally hidden" you want to know if ALL corners are either inside the dragged-item boundary or outside the viewport. For partially hidden you're looking for a single corner matching the same test.

I don't think checking the element's own visibility and display properties is good enough for requirement #1, even if you use currentStyle/getComputedStyle. You also have to check the element's ancestors. If an ancestor is hidden, so is the element.

Check elements' offsetHeight property. If it is more than 0, it is visible. Note: this approach doesn't cover a situation when visibility:hidden style is set. But that style is something weird anyways.

Here is a sample script and test case. Covers positioned elements, visibilty: hidden, display: none. Didn't test z-index, assume it works.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title></title>
<style type="text/css">
div {
width: 200px;
border: 1px solid red;
}
p {
border: 2px solid green;
}
.r {
border: 1px solid #BB3333;
background: #EE9999;
position: relative;
top: -50px;
height: 2em;
}
.of {
overflow: hidden;
height: 2em;
word-wrap: none;
}
.of p {
width: 100%;
}
.of pre {
display: inline;
}
.iv {
visibility: hidden;
}
.dn {
display: none;
}
</style>
<script src="http://www.prototypejs.org/assets/2008/9/29/prototype-1.6.0.3.js"></script>
<script>
function isVisible(elem){
if (Element.getStyle(elem, 'visibility') == 'hidden' || Element.getStyle(elem, 'display') == 'none') {
return false;
}
var topx, topy, botx, boty;
var offset = Element.positionedOffset(elem);
topx = offset.left;
topy = offset.top;
botx = Element.getWidth(elem) + topx;
boty = Element.getHeight(elem) + topy;
var v = false;
for (var x = topx; x <= botx; x++) {
for(var y = topy; y <= boty; y++) {
if (document.elementFromPoint(x,y) == elem) {
// item is visible
v = true;
break;
}
}
if (v == true) {
break;
}
}
return v;
}
window.onload=function() {
var es = Element.descendants('body');
for (var i = 0; i < es.length; i++ ) {
if (!isVisible(es[i])) {
alert(es[i].tagName);
}
}
}
</script>
</head>
<body id='body'>
<div class="s"><p>This is text</p><p>More text</p></div>
<div class="r">This is relative</div>
<div class="of"><p>This is too wide...</p><pre>hidden</pre>
<div class="iv">This is invisible</div>
<div class="dn">This is display none</div>
</body>
</html>

Here is a part of the response that tells you if an element is in the viewport.
You may need to check if there is nothing on top of it using elementFromPoint, but it's a bit longer.
function isInViewport(element) {
var rect = element.getBoundingClientRect();
var windowHeight = window.innerHeight || document.documentElement.clientHeight;
var windowWidth = window.innerWidth || document.documentElement.clientWidth;
return rect.bottom > 0 && rect.top < windowHeight && rect.right > 0 && rect.left < windowWidth;
}

Using .outerWidth() & .outerHeight() with the 'resize' event to center a child element in parent

I am attempting to write some JavaScript code that will allow me to center a child element within it's parent using padding. Then using the same function to recalculate the spacing using the 'resize' event. Before you start asking me why i am not doing this with CSS, this code is only a small part of a larger project. I have simplified the code as the rest of the code works and would only serve to confuse the subject.
Calculating the space - This is the function that caculates the amount of space to be used on either side of the child element.
($outer.outerWidth() - $inner.outerWidth()) / 2;
($outer.outerHeight() - $inner.outerHeight()) / 2;
The problem
Although i have successfully managed to get the desired results with margin. Padding is causing me problems.
It appears to be increasing the width on the outer element when resized
It does not center the child element perfectly (there appears to be an offset)
The inner element collapses on resize and becomes invisible.
I realize that there may be some fundamentals regarding padding that are causing my problems however after numerous console logs and observing the data returned i still can't put my finger on the problem. Any suggestion would be very welcome. It may turn out that this is not feasible at all.
HTML
<div id="demo" class="outer">
<div class="inner">
</div>
</div>
CSS
html {
box-sizing: border-box;
}
*, *:before, *:after {
box-sizing: inherit;
}
.outer {
width:97%;
height:400px;
border:1px solid black;
margin:20px;
}
.inner {
width:40%;
height:100px;
background-color:grey;
}
JAVASCRIPT
var $outer = $(".outer");
var $inner = $(".inner");
var getSpace = function(axis) {
if (axis.toLowerCase() == "x") {
return ($outer.outerWidth() - $inner.outerWidth()) / 2;
} else if (axis.toLowerCase() == "y") {
return ($outer.outerHeight() - $inner.outerHeight()) / 2;
}
}
var renderStyle = function(spacingType) {
var lateralSpace = getSpace("x");
var verticalSpace = getSpace("y");
var $element;
if (spacingType == "padding") {
$element = $outer;
} else if (spacingType == "margin") {
$element = $inner;
}
$.each(["top", "right", "bottom", "left"], function(index, direction) {
if (direction == "top" || direction == "bottom") {
$element.css(spacingType + "-" + direction, verticalSpace);
}
else if (direction == "right" || direction == "left") {
$element.css(spacingType + "-" + direction, lateralSpace);
}
});
};
var renderInit = function() {
$(document).ready(function() {
renderStyle("padding");
});
$(window).on("resize", function() {
renderStyle("padding");
});
}
renderInit();
EXAMPLE - link

Although I completely disagree with this approach to horizontally centring an element, hopefully this will help you on your way.
Fiddle: https://jsfiddle.net/0uxx2ujg/
JavaScript:
var outer = $('.outer'), inner = $('.inner');
function centreThatDiv(){
var requiredPadding = outer.outerWidth() / 2 - (inner.outerWidth() / 2);
console.log(requiredPadding);
outer.css('padding', '0 ' + requiredPadding + 'px').css('width','auto');
}
$(document).ready(function(){
// fire on page load
centreThatDiv();
});
$(window).resize(function(){
// fire on window resize
centreThatDiv();
});
HTML:
<div class="outer">
<div class="inner">Centre me!</div>
</div>
CSS:
.outer{ width:80%; height:300px; margin:10%; background: tomato; }
.inner{ width:60px; height:60px; background:white; }
Furthered on from why I disagree with this approach - JavaScript shouldn't be used to lay things out. Sure - it can be, if it really needs to be used; but for something as simple as centring an element, it's not necessary at all. Browsers handle resizing CSS elements themselves, so by using JS you introduce more headaches for yourself further down the line.
Here's a couple of examples of how you can achieve this in CSS only:
text-align:center & display:inline-block https://jsfiddle.net/0uxx2ujg/1/
position:absolute & left:50% https://jsfiddle.net/0uxx2ujg/2/ (this can be used for vertically centring too which is trickier than horizontal)

You can create the new CSS class to adjust for elements size on $window.onresize = function () {
//add your code
};

Trigger event when user scroll to specific element - with jQuery

I have an h1 that is far down a page..
<h1 id="scroll-to">TRIGGER EVENT WHEN SCROLLED TO.</h1>
and I want to trigger an alert when the user scrolls to the h1, or has it in it's browser's view.
$('#scroll-to').scroll(function() {
alert('you have scrolled to the h1!');
});
how do I do this?

You can calculate the offset of the element and then compare that with the scroll value like:
$(window).scroll(function() {
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!');
}
});
Check this Demo Fiddle
Updated Demo Fiddle no alert -- instead FadeIn() the element
Updated code to check if the element is inside the viewport or not. Thus this works whether you are scrolling up or down adding some rules to the if statement:
if (wS > (hT+hH-wH) && (hT > wS) && (wS+wH > hT+hH)){
//Do something
}
Demo Fiddle

Combining this question with the best answer from jQuery trigger action when a user scrolls past a certain part of the page
var element_position = $('#scroll-to').offset().top;
$(window).on('scroll', function() {
var y_scroll_pos = window.pageYOffset;
var scroll_pos_test = element_position;
if(y_scroll_pos > scroll_pos_test) {
//do stuff
}
});
UPDATE
I've improved the code so that it will trigger when the element is half way up the screen rather than at the very top. It will also trigger the code if the user hits the bottom of the screen and the function hasn't fired yet.
var element_position = $('#scroll-to').offset().top;
var screen_height = $(window).height();
var activation_offset = 0.5;//determines how far up the the page the element needs to be before triggering the function
var activation_point = element_position - (screen_height * activation_offset);
var max_scroll_height = $('body').height() - screen_height - 5;//-5 for a little bit of buffer
//Does something when user scrolls to it OR
//Does it when user has reached the bottom of the page and hasn't triggered the function yet
$(window).on('scroll', function() {
var y_scroll_pos = window.pageYOffset;
var element_in_view = y_scroll_pos > activation_point;
var has_reached_bottom_of_page = max_scroll_height <= y_scroll_pos && !element_in_view;
if(element_in_view || has_reached_bottom_of_page) {
//Do something
}
});

I think your best bet would be to leverage an existing library that does that very thing:
http://imakewebthings.com/waypoints/
You can add listeners to your elements that will fire off when your element hits the top of the viewport:
$('#scroll-to').waypoint(function() {
alert('you have scrolled to the h1!');
});
For an amazing demo of it in use:
http://tympanus.net/codrops/2013/07/16/on-scroll-header-effects/

Inview library triggered event and works well with jquery 1.8 and higher!
https://github.com/protonet/jquery.inview
$('div').on('inview', function (event, visible) {
if (visible == true) {
// element is now visible in the viewport
} else {
// element has gone out of viewport
}
});
Read this https://remysharp.com/2009/01/26/element-in-view-event-plugin

Fire scroll only once after a successful scroll
Note: By successful scroll I mean when the user has scrolled to the desired
element or in other words when the desired element is in view
The accepted answer worked 90% for me so I had to tweak it a little to actually fire only once.
$(window).on('scroll',function() {
var hT = $('#comment-box-section').offset().top,
hH = $('#comment-box-section').outerHeight(),
wH = $(window).height(),
wS = $(this).scrollTop();
if (wS > ((hT+hH-wH)-500)){
console.log('comment box section arrived! eh');
// This detaches the scroll so doStuff() won't run more than once
$(window).off('scroll');
doStuff();
}
});

You could use this for all devices,
$(document).on('scroll', function() {
if( $(this).scrollTop() >= $('#target_element').position().top ){
do_something();
}
});

Intersection Observer can be the best thing IMO, without any external library it does a really good job.
const options = {
root: null,
threshold: 0.25, // 0 - 1 this work as a trigger.
rootMargin: '150px'
};
const target = document.querySelector('h1#scroll-to');
const observer = new IntersectionObserver(
entries => { // each entry checks if the element is the view or not and if yes trigger the function accordingly
entries.forEach(() => {
alert('you have scrolled to the h1!')
});
}, options);
observer.observe(target);

You can use jQuery plugin with the inview event like this :
jQuery('.your-class-here').one('inview', function (event, visible) {
if (visible == true) {
//Enjoy !
}
});
Link : https://remysharp.com/2009/01/26/element-in-view-event-plugin

This should be what you need.
Javascript:
$(window).scroll(function() {
var hT = $('#circle').offset().top,
hH = $('#circle').outerHeight(),
wH = $(window).height(),
wS = $(this).scrollTop();
console.log((hT - wH), wS);
if (wS > (hT + hH - wH)) {
$('.count').each(function() {
$(this).prop('Counter', 0).animate({
Counter: $(this).text()
}, {
duration: 900,
easing: 'swing',
step: function(now) {
$(this).text(Math.ceil(now));
}
});
}); {
$('.count').removeClass('count').addClass('counted');
};
}
});
CSS:
#circle
{
width: 100px;
height: 100px;
background: blue;
-moz-border-radius: 50px;
-webkit-border-radius: 50px;
border-radius: 50px;
float:left;
margin:5px;
}
.count, .counted
{
line-height: 100px;
color:white;
margin-left:30px;
font-size:25px;
}
#talkbubble {
width: 120px;
height: 80px;
background: green;
position: relative;
-moz-border-radius: 10px;
-webkit-border-radius: 10px;
border-radius: 10px;
float:left;
margin:20px;
}
#talkbubble:before {
content:"";
position: absolute;
right: 100%;
top: 15px;
width: 0;
height: 0;
border-top: 13px solid transparent;
border-right: 20px solid green;
border-bottom: 13px solid transparent;
}
HTML:
<div id="talkbubble"><span class="count">145</span></div>
<div style="clear:both"></div>
<div id="talkbubble"><span class="count">145</span></div>
<div style="clear:both"></div>
<div id="circle"><span class="count">1234</span></div>
Check this bootply:
http://www.bootply.com/atin_agarwal2/cJBywxX5Qp

If you are looking for a javascript version. You can call this method on scroll event listener.
showScrollTop = () =>{
const currentScrollPosition = window.pageYOffset;
let elementID = 'service-selector'
const elementOffsetTop = document.getElementById(elementID).offsetTop
if ( currentScrollPosition > elementOffsetTop){
// place your logic here
} else {
// place your logic here
}
}
window.addEventListener('scroll', showScrollTop)

If you are doing a lot of functionality based on scroll position, Scroll magic (http://scrollmagic.io/) is built entirely for this purpose.
It makes it easy to trigger JS based on when the user reaches certain elements when scrolling. It also integrates with the GSAP animation engine (https://greensock.com/) which is great for parallax scrolling websites

Just a quick modification to DaniP's answer, for anyone dealing with elements that can sometimes extend beyond the bounds of the device's viewport.
Added just a slight conditional - In the case of elements that are bigger than the viewport, the element will be revealed once it's top half has completely filled the viewport.
function elementInView(el) {
// The vertical distance between the top of the page and the top of the element.
var elementOffset = $(el).offset().top;
// The height of the element, including padding and borders.
var elementOuterHeight = $(el).outerHeight();
// Height of the window without margins, padding, borders.
var windowHeight = $(window).height();
// The vertical distance between the top of the page and the top of the viewport.
var scrollOffset = $(this).scrollTop();
if (elementOuterHeight < windowHeight) {
// Element is smaller than viewport.
if (scrollOffset > (elementOffset + elementOuterHeight - windowHeight)) {
// Element is completely inside viewport, reveal the element!
return true;
}
} else {
// Element is larger than the viewport, handle visibility differently.
// Consider it visible as soon as it's top half has filled the viewport.
if (scrollOffset > elementOffset) {
// The top of the viewport has touched the top of the element, reveal the element!
return true;
}
}
return false;
}

I use the same code doing that all the time, so added a simple jquery plugin doing it.
480 bytes long, and fast. Only bound elements analyzed in runtime.
https://www.npmjs.com/package/jquery-on-scrolled-to
It will be
$('#scroll-to').onScrolledTo(0, function() {
alert('you have scrolled to the h1!');
});
or use 0.5 instead of 0 if need to alert when half of the h1 shown.

Quick and fast implementation,
let triggered = false;
$(window).on('scroll',function() {
if (window.scrollY > ($('#scrollTo').offset().top+$('#scrollTo').outerHeight()-window.innerHeight) & !triggered){
console.log('triggered here on scroll..');
triggered = true;
}
});
using global variable triggered = false makes it just to happen once, otherwise, every time crossing past the element, this action is triggered.

How to propagate a click to all divs under cursor?

I have a bunch of divs positioned absolutely on top of each other. When I bind a click event to all of them, only the top div responds. How can I send the event to all divs under the cursor?

Taking FelixKling's suggestion to use document.elementFromPoint() and Amberlamps's fiddle, and employing jQuery for the DOM interactions, I ended up with the following :
$divs = $("div").on('click.passThrough', function (e, ee) {
var $el = $(this).hide();
try {
console.log($el.text());//or console.log(...) or whatever
ee = ee || {
pageX: e.pageX,
pageY: e.pageY
};
var next = document.elementFromPoint(ee.pageX, ee.pageY);
next = (next.nodeType == 3) ? next.parentNode : next //Opera
$(next).trigger('click.passThrough', ee);
} catch (err) {
console.log("click.passThrough failed: " + err.message);
} finally {
$el.show();
}
});
DEMO
try/catch/finally is used to ensure elements are shown again, even if an error occurs.
Two mechanisms allow the click event to be passed through or not :
attaching the handler to only selected elements (standard jQuery).
namespacing the click event, click.passThrough analogous to event.stopPropagation().
Separately or in combination, these mechanisms offer some flexibility in controlling the attachment and propagation of "passThrough" behaviour. For example, in the DEMO, try removing class p from the "b" element and see how the propagation behaviour has changed.
As it stands, the code needs to be edited to get different application-level behaviour. A more generalized solution would :
allow for programmatic attachment of app-specific behaviour
allow for programmatic inhibition of "passThrough" propagation, analogous to event.stopPropagation().
Both of these ambitions might be achieved by establishing a clickPassthrough event in jQuery, with underlying "passThrough" behaviour, but more work would be involved to achieve that. Maybe someone would like to have a go.

This is not as easy as you might think. This is a solution that I came up with. I only tested it in Chrome and I did not use any framework.
The following snippet is just for add a click event to every div in the document, that outputs its class name when triggered.
var divs = document.getElementsByTagName("div");
for(var i = 0; i < divs.length; i++) {
divs[i].onclick = function() {
console.log("class clicked: " + this.className);
};
}
Attaching a click event to the body element so that every single click event is noticed by our script.
if(document.addEventListener) {
document.body.addEventListener("click", countDivs);
} else if(document.attachEvent) {
document.attachEvent("onclick", countDivs);
}
Iterate through all divs that you want to check (you might want to adjust here to your preferred range of divs). Generate their computed style and check whether the mouse coordinates are within the range of the div´s position plus its width and height. Do not trigger click event when the div is our source element because the click event has already been fired by then.
function countDivs(e) {
e = e || window.event;
for(var i = 0; i < divs.length; i++) {
var cStyle = window.getComputedStyle(divs[i]);
if(divs[i] !== e.target && e.pageX >= parseInt(cStyle.left) && e.pageX <= (parseInt(cStyle.left) + parseInt(cStyle.width)) && e.pageY >= parseInt(cStyle.top) && e.pageY <= (parseInt(cStyle.top) + parseInt(cStyle.height))) {
divs[i].click();
}
}
}
CSS:
.a, .b, .c {
position: absolute;
height: 100px;
width: 100px;
border: 1px #000 solid
}
.a {
top: 100px;
left: 100px;
}
.b {
top: 120px;
left: 120px;
}
.c {
top: 140px;
left: 140px;
}
HTML:
<div class="a"></div>
<div class="b"></div>
<div class="c"></div>
I also added a jsFiddle

A simple way could be to use elementFromPoint():
http://jsfiddle.net/SpUeN/1/
var clicks = 0,cursorPosition={};
$('div').click(function (e) {
if(typeof cursorPosition.X === 'undefined') {
cursorPosition.X = e.pageX;
cursorPosition.Y = e.pageY;
}
clicks++;
e.stopPropagation();
$(this).addClass('hided');
var underELEM = document.elementFromPoint(cursorPosition.X, cursorPosition.Y);
if (underELEM.nodeName.toUpperCase() === "DIV") $(underELEM).click();
else {
$('#clicks').html("Clicks: " + clicks);
$('.hided').removeClass('hided');
clicks=0;
cursorPosition = {};
}
});

If you are stacking elements absolutely it may be simpler to stack them all in a positioned container, and handle the events from this parent. You can then manipulate its children without having to measure anything.

Twitter-style autocomplete in textarea

I am looking for a Javascript autocomplete implementation which includes the following:
Can be used in a HTML textarea
Allows for typing regular text without invoking autocomplete
Detects the # character and starts autocomplete when it is typed
Loads list of options through AJAX
I believe that this is similar to what Twitter is doing when tagging in a tweet, but I can't find a nice, reusable implementation.
A solution with jQuery would be perfect.
Thanks.

Another great library which solves this problem At.js (deprecated)
Source
Demo
They are now suggesting the Tribute library
https://github.com/zurb/tribute
Example

I'm sure your problem is long since solved, but jquery-textcomplete looks like it would do the job.

Have you tried this
GITHUB: https://github.com/podio/jquery-mentions-input
DEMO/CONFIG: http://podio.github.io/jquery-mentions-input/
It is pretty simple to implement.

I've created a Meteor package for this purpose. Meteor's data model allows for fast multi-rule searching with custom rendered lists. If you're not using Meteor for your web app, (I believe) you unfortunately won't find anything this awesome for autocompletion.
Autocompleting users with #, where online users are shown in green:
In the same line, autocompleting something else with metadata and bootstrap icons:
Fork, pull, and improve:
https://github.com/mizzao/meteor-autocomplete

Try this:
(function($){
$.widget("ui.tagging", {
// default options
options: {
source: [],
maxItemDisplay: 3,
autosize: true,
animateResize: false,
animateDuration: 50
},
_create: function() {
var self = this;
this.activeSearch = false;
this.searchTerm = "";
this.beginFrom = 0;
this.wrapper = $("<div>")
.addClass("ui-tagging-wrap");
this.highlight = $("<div></div>");
this.highlightWrapper = $("<span></span>")
.addClass("ui-corner-all");
this.highlightContainer = $("<div>")
.addClass("ui-tagging-highlight")
.append(this.highlight);
this.meta = $("<input>")
.attr("type", "hidden")
.addClass("ui-tagging-meta");
this.container = $("<div></div>")
.width(this.element.width())
.insertBefore(this.element)
.addClass("ui-tagging")
.append(
this.highlightContainer,
this.element.wrap(this.wrapper).parent(),
this.meta
);
var initialHeight = this.element.height();
this.element.height(this.element.css('lineHeight'));
this.element.keypress(function(e) {
// activate on #
if (e.which == 64 && !self.activeSearch) {
self.activeSearch = true;
self.beginFrom = e.target.selectionStart + 1;
}
// deactivate on space
if (e.which == 32 && self.activeSearch) {
self.activeSearch = false;
}
}).bind("expand keyup keydown change", function(e) {
var cur = self.highlight.find("span"),
val = self.element.val(),
prevHeight = self.element.height(),
rowHeight = self.element.css('lineHeight'),
newHeight = 0;
cur.each(function(i) {
var s = $(this);
val = val.replace(s.text(), $("<div>").append(s).html());
});
self.highlight.html(val);
newHeight = self.element.height(rowHeight)[0].scrollHeight;
self.element.height(prevHeight);
if (newHeight < initialHeight) {
newHeight = initialHeight;
}
if (!$.browser.mozilla) {
if (self.element.css('paddingBottom') || self.element.css('paddingTop')) {
var padInt =
parseInt(self.element.css('paddingBottom').replace('px', '')) +
parseInt(self.element.css('paddingTop').replace('px', ''));
newHeight -= padInt;
}
}
self.options.animateResize ?
self.element.stop(true, true).animate({
height: newHeight
}, self.options.animateDuration) :
self.element.height(newHeight);
var widget = self.element.autocomplete("widget");
widget.position({
my: "left top",
at: "left bottom",
of: self.container
}).width(self.container.width()-4);
}).autocomplete({
minLength: 0,
delay: 0,
maxDisplay: this.options.maxItemDisplay,
open: function(event, ui) {
var widget = $(this).autocomplete("widget");
widget.position({
my: "left top",
at: "left bottom",
of: self.container
}).width(self.container.width()-4);
},
source: function(request, response) {
if (self.activeSearch) {
self.searchTerm = request.term.substring(self.beginFrom);
if (request.term.substring(self.beginFrom - 1, self.beginFrom) != "#") {
self.activeSearch = false;
self.beginFrom = 0;
self.searchTerm = "";
}
if (self.searchTerm != "") {
if ($.type(self.options.source) == "function") {
self.options.source(request, response);
} else {
var re = new RegExp("^" + escape(self.searchTerm) + ".+", "i");
var matches = [];
$.each(self.options.source, function() {
if (this.label.match(re)) {
matches.push(this);
}
});
response(matches);
}
}
}
},
focus: function() {
// prevent value inserted on focus
return false;
},
select: function(event, ui) {
self.activeSearch = false;
//console.log("#"+searchTerm, ui.item.label);
this.value = this.value.replace("#" + self.searchTerm, ui.item.label) + ' ';
self.highlight.html(
self.highlight.html()
.replace("#" + self.searchTerm,
$("<div>").append(
self.highlightWrapper
.text(ui.item.label)
.clone()
).html()+' ')
);
self.meta.val((self.meta.val() + " #[" + ui.item.value + ":]").trim());
return false;
}
});
}
});
body, html {
font-family: "lucida grande",tahoma,verdana,arial,sans-serif;
}
.ui-tagging {
position: relative;
border: 1px solid #B4BBCD;
height: auto;
}
.ui-tagging .ui-tagging-highlight {
position: absolute;
padding: 5px;
overflow: hidden;
}
.ui-tagging .ui-tagging-highlight div {
color: transparent;
font-size: 13px;
line-height: 18px;
white-space: pre-wrap;
}
.ui-tagging .ui-tagging-wrap {
position: relative;
padding: 5px;
overflow: hidden;
zoom: 1;
border: 0;
}
.ui-tagging div > span {
background-color: #D8DFEA;
font-weight: normal !important;
}
.ui-tagging textarea {
display: block;
font-family: "lucida grande",tahoma,verdana,arial,sans-serif;
background: transparent;
border-width: 0;
font-size: 13px;
height: 18px;
outline: none;
resize: none;
vertical-align: top;
width: 100%;
line-height: 18px;
overflow: hidden;
}
.ui-autocomplete {
font-size: 13px;
background-color: white;
border: 1px solid black;
margin-bottom: -5px;
width: 0;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<textarea></textarea>
http://jsfiddle.net/mekwall/mcWnL/52/
This link will help you

I could not find any solution that matched my requirements perfectly, so I ended up with the following:
I use the jQuery keypress() event to check for the user pressing the # character.
If this is the case, a modal dialog is shown using jQuery UI. This dialog contains an autocomplete text field (many options can be used here, but I recommmend jQuery Tokeninput)
When the user selects an option in the dialog, a tag is added to the text field and the dialog is closed.
This is not the most elegant solution, but it works and it does not require extra keypresses compared to my original design.
Edit
So basically, we have our large text box where the user can enter text. He should be able to "tag" a user (this just means inserting #<userid> in the text). I attach to the jQuery keyup event and detect the # character using (e.which == 64) to show a modal with a text field for selecting the users to tag.
The meat of the solution is simply this modal dialog with a jQuery Tokeninput text box. As the user types here, the list of users is loaded through AJAX. See the examples on the website for how to use it properly. When the user closes the dialog, I insert the selected IDs into the large text box.

Recently i had to face this problem and this is how i nailed down...
Get the string index at the cursor position in the textarea by using selectionStart
slice the string from index 0 to the cursor position
Insert it into a span (since span has multiple border boxes)
Get the dimensions of the border box using element.getClientRects() relative to the view port. (here is the MDN Reference)
Calculate the top and left and feed it to the dropdown
This works in all latest browsers. haven't tested at old ones
Here is Working bin

Another plugin which provides similar functionality:
AutoSuggest
You can use it with custom triggers or you can use it without any triggers. Works with input fields, textareas and contenteditables. And jQuery is not a dependency.

I would recommend the textcomplete plugin. No jQuery dependency. You may need bootstrap.css to refer, but I recommend to write your own CSS, lighter and simple.
Follow the below steps to give it a try
npm install #textcomplete/core #textcomplete/textarea
Bind it to your input element
const editor = new TextareaEditor(inputEl);
const textcomplete = new Textcomplete(editor, strategy, options);
Set strategy(how to fetch suggestion list) and options(settings to configure the suggestions) according to your need.
JS version
Angular Version

This small extension seems to be the closest at least in presentation to what was asked. Since it's small, it can be easily understood and modified. http://lookapanda.github.io/jquery-hashtags/

THIS should work. With regards to the # kicking off the search, just add (dynamically or not) the symbol to the beginning of each possible search term.