I want that the div I created will move when the mouse is getting near to him.
Here is the fiddle link: http://jsfiddle.net/jLAq3/2/
Basic starting code (because I don't have a clue how to do it):
$('#leaf').();
Bind a function to the movement of the mouse. As the mouse moves:
Get the coordinates of the element.
Get the coordinates of the cursor.
Compare cursor coordinates with element coordinates.
If cursor is near element, move element - else do nothing.
Easy stuff.
This is a start. Every time the mouse is moving outside the leaf then a message appears.
$('body').mousemove(function(e){
var w = $('#leaf').outerWidth(),
h = $('#leaf').outerHeight(),
x = e.pageX,
y = e.pageY;
if(x > w && y > h)
{
console.log("The leaf is moving");
}
})
Furthermore you can apply some css with js to the leaf for movement etc. In a more complex example you have to spot more carefully the position and not simply rely on the width and the height of the image.
Here is a start.
http://jsfiddle.net/Lpg8x/80/
$( 'body' ).mousemove( function( event ) {
if( isNear( $( '#near' ), 20, event ) ) {
$( '#near' ).html( 'is near!' );
} else {
$( '#near' ).empty();
};
} );
function isNear( $element, distance, event ) {
var left = $element.offset().left - distance,
top = $element.offset().top - distance,
right = left + $element.width() + ( 2 * distance ),
bottom = top + $element.height() + ( 2 * distance ),
x = event.pageX,
y = event.pageY;
return ( x > left && x < right && y > top && y < bottom );
};
Have fun!
Here is a basic working example of how you actually would do all that
http://jsfiddle.net/jLAq3/10/
var leafX = 0, leafY = 0;
$('#leaf').css({position: 'relative'});
$(document).mousemove(function(e){
var offset = $('#leaf').offset()
,x1 = offset.left - 20
,x2 = offset.left + $('#leaf').width() + 20
,y1 = offset.top
,y2 = offset.top + $('#leaf').height() + 20
,center, mousePos
;
if(e.pageX > x1 && e.pageX < x2 && e.pageY > y1 && e.pageY < y2) {
center = (x2 - x1) / 2;
mousePos = e.pageX - x1;
if(mousePos < center) {
leafX += 20;
} else {
leafX -= 20;
}
center = (y2 - y1) / 2;
mousePos = e.pageY - y1;
if(mousePos < center) {
leafY += 20;
} else {
leafY -= 20;
}
}
$('#leaf').css({ top : leafY + 'px', left : leafX + 'px'});
});
But you should really learn the basics of DHTML before jumping into things, for example the difference between position absolute and relative, how to actually move HTML elements, layering, event binding etc.
Here are couple of good resources:
http://www.quirksmode.org/sitemap.html
http://www.w3schools.com/
I'm using 2 Javscript methods to position a hovering button inside a static element on my page. The button that is centered is inputted inside the first element and uses position absolute. The code I'm using to get the parent element measurements:
// calculate if the element is in the visible window
function elementVisibleRect(element) {
element = $(element);
var rect = {
top: Math.round(element.offset().top),
left: Math.round(element.offset().left),
width: Math.round(element.outerWidth()),
height: Math.round(element.outerHeight())
};
var scrollTop = $(window).scrollTop();
var windowHeight = $(window).height();
var scrollBottom = scrollTop + windowHeight;
var elementBottom = Math.round(rect.height + rect.top);
if (scrollTop < rect.top && scrollBottom > elementBottom) {
return rect;
}
if (scrollTop > rect.top) {
rect.top = scrollTop;
}
if (scrollBottom < elementBottom) {
rect.height = scrollBottom - rect.top;
} else {
rect.height = windowHeight - (scrollBottom - elementBottom);
}
return rect;
}
and for using this information and centering the button inside
// center the element based on visible screen-frame
function elementPosition (element) {
var visibleRect = elementVisibleRect(element);
$('.editHoverButton').css({
top: visibleRect.top + ((visibleRect.height / 2) - ($('.editHoverButton').outerHeight() / 2)),
left: visibleRect.left + (visibleRect.width / 2) - ($('.editHoverButton').outerWidth() / 2)
});
}
Now my problem is that a third party library requires the parent DIV to change position from the browser default "static" to "relative" which breaks my calculations in the second function.
It might be late, but no matter what I try I can't seem to figure out how to get this working for when the parent element has position set to relative. I can't seem to get the maths quite right, and my head is beginning to hurt. Any suggestions?
EDIT - ADDED JSFIDDLE
http://jsfiddle.net/RhTY6/
Elements with absolute positioning are removed from the natural flow (e.g. they don't leave a space where they were) and positioned relative to their first parent with non-static positioning. Since the positioning of the right-hand box is relative (not static), you can position the button with top: 50%; and left: 50%;. This will make the top-left corner at the center of the parent. Then all you have to do is subtract half the element's height and width from the position, using margin-top and margin-left. This is much simpler than what you were doing, as you can see below:
JavaScript:
function elementPosition() {
$('.editHoverButton').css('margin-top', 0 - $('.editHoverButton').outerHeight() / 2);
$('.editHoverButton').css('margin-left', 0 - $('.editHoverButton').outerWidth() / 2);
};
CSS:
.editHoverButton {
position: absolute;
z-index: 99;
font-family: sans-serif;
font-size: 14px;
font-weight: normal;
background-color: #00bb00;
top: 50%;
left: 50%;
}
Nothing else has to change except to remove this from the elementPosition() function.
DEMO (Notice that the left one no longer works. This is because it is positioned static.)
EDIT--Using the same basic idea, this method should work:
The problem is that you have take the top and left positions of the element when defining rect. on the positioning calculations. Changing those to 0 (not the best method, but it works) fixes the problem for relative elements.
DEMO (Notice that the left one now does work. This is because it is positioned at 0,0 anyway.)
EDIT--This will work when the page scrolls:
This sets the container in a variable so that when the page scrolls, it can be repositioned automatically.
DEMO
EDIT: made it worked with your CSS and HTML (relative and absolute positioning) by altering the Script only.
The horizontal axis calcs were completely missing (I've applied the same calcs you applied to the vertical axis).
I've added some data and a ruler to help you finish the job: as you can see, it is (and it was, in your original fiddle) not perfectly centered (obviously you need to look at it when the container is smaller than the viewport), but this will be easy to work out.
Running Demo
Try to resize the fiddle window and to scroll both vertically and horizontally to see it works.
function elementVisibleRect(element) {
$("#data").html("");
element = $(element);
var rect = {
top: Math.round(element.offset().top),
left: Math.round(element.offset().left),
width: Math.round(element.outerWidth()),
height: Math.round(element.outerHeight())
};
var scrollTop = $(window).scrollTop();
var windowHeight = $(window).height();
var scrollBottom = scrollTop + windowHeight;
var elementBottom = Math.round(rect.height + rect.top);
var scrollLeft = $(window).scrollLeft();
var windowWidth = $(window).width();
var scrollRight = scrollLeft + windowWidth;
var elementRight = Math.round(rect.width + rect.left);
addData("rect.top", rect.top);
addData("rect.left", rect.left);
addData("rect.width", rect.width);
addData("rect.height", rect.height);
addData("scrollTop", scrollTop);
addData("windowHeight", windowHeight);
addData("scrollBottom", scrollBottom);
addData("elementBottom", elementBottom);
addData("scrollLeft", scrollLeft);
addData("windowWidth", windowWidth);
addData("scrollRight", scrollRight);
addData("elementRight", elementRight);
if (rect.top < scrollTop) {
rect.top = scrollTop;
}
if (scrollBottom < rect.top < scrollTop) {
rect.top = scrollTop;
}
if (scrollBottom < elementBottom) {
rect.height = scrollBottom - rect.top;
} else {
rect.height = windowHeight - (scrollBottom - elementBottom);
}
if (rect.left < scrollLeft) {
rect.left = scrollLeft;
}
if (scrollRight < rect.left < scrollLeft) {
rect.left = scrollLeft;
}
if (scrollRight < elementRight) {
rect.width = scrollRight - rect.left;
} else {
rect.width = windowWidth - (scrollRight - elementRight);
}
return rect;
}
As you can see the image below, there is "A", "B", "C", "D" and "E" on the website, and the user may only can see the A, B, and a little parts of D in their browser. They need to require to scroll down the browser or some users may have a bigger screen, or a longer window on their browser that allow they can even see the element C.
Ok, my question is, is this possible to let me know what the user seeing on their browser using javascript? In this element, is "A", "B" and "D".
Using the following, you can get the browser's viewport size.
window.innerHeight;
window.innerWidth;
Refer to: http://www.javascripter.net/faq/browserw.htm
If you want to detect how far they have scrolled down the page, you can use
window.scrollX; // Horizontal scrolling
window.scrollY; // Vertical scrolling
Also, I have found a window object - window.screen. On my system it has the following data:
window.screen.availHeight = 994;
window.screen.availLeft = 0;
window.screen.availTop = 0;
window.screen.availWidth = 1280;
window.screen.colorDepth = 32;
window.screen.height = 1280;
window.screen.pixelDepth = 32;
window.screen.width = 1280;
Try it :) http://jsfiddle.net/Aj2fU/5/
$('input').click(function(){
// check for visible divs with class 'check'
$('.check').each(function(){
var pos = $(this).offset(),
wX = $(window).scrollLeft(), wY = $(window).scrollTop(),
wH = $(window).height(), wW = $(window).width(),
oH = $(this).outerHeight(), oW = $(this).outerWidth();
// check the edges
// left, top and right, bottom are in the viewport
if (pos.left >= wX && pos.top >= wY &&
oW + pos.left <= wX + wW && oH + pos.top <= wY + wH )
alert('Div #' + $(this).attr('id') + ' is fully visible');
else // partially visible
if (((pos.left <= wX && pos.left + oW > wX) ||
(pos.left >= wX && pos.left <= wX + wW)) &&
((pos.top <= wY && pos.top + oH > wY) ||
(pos.top >= wY && pos.top <= wY + wH)))
alert('Div #' + $(this).attr('id') + ' is partially visible');
else // not visible
alert('Div #' + $(this).attr('id') + ' is not visible');
});
});
Updated to work with very wide divs. Basically it checks whether the left, top and right, bottom edges of the divs are both in the visible part of the screen, partially or outside of the viewport.
Basically, you'd first have to measure the viewport dimentions, by using the window object, then you'd need to loop through each of the elements that you want to check, and calculate wether they fit.
See this jsfiddle for an example.
Here's the code (for posterity's sake):
HTML:
<div id="info">
<p class="wxh"></p>
<p class="txl"></p>
<p class="report"></p>
</div>
<h1>A big list!</h1>
<ul></ul>
CSS:
#info{
position: fixed;
right: 0px;
text-align: center;
background: white;
border: 2px solid black;
padding: 10px;
}
JS:
$(function(){
$(window).bind('scroll.measure resize.measure',function(){
// Gather together the window width, height, and scroll position.
var winWidth = $(window).width(),
winHeight = $(window).height(),
winLeft = $(window).scrollLeft(),
winTop = $(window).scrollTop(),
winBottom = winTop + winHeight,
winRight = winLeft + winWidth,
inView = [];
// Loop over each of the elements you want to check
$('.inview').each(function(){
// Get the elements position and dimentions.
var pos = $(this).position(),
width = $(this).outerWidth(),
height = $(this).outerHeight();
// Set bottom and right dimentions.
pos.bottom = pos.top + height;
pos.right = pos.left + width;
// Check whether this element is partially within
// the window's visible area.
if((
pos.left >= winLeft &&
pos.top >= winTop &&
pos.right <= winRight &&
pos.bottom <= winBottom
) || (
pos.left >= winLeft && pos.top >= winTop &&
pos.left <= winRight && pos.top <= winBottom
) || (
pos.right <= winRight && pos.bottom <= winBottom &&
pos.right >= winLeft && pos.bottom >= winTop
)){
// Change this to push the actual element if you need it.
inView.push( $(this).text() );
}
});
// For the purposes of this example, we only need the
// first and last element, but in your application you may need all.
var first = inView.shift(),
last = inView.pop();
// Show the details in the info box.
$('#info .wxh').text( winWidth+' x '+winHeight );
$('#info .txl').text( winTop+' x '+winLeft );
$('#info .report').text( 'Showing from '+first+' to '+last );
});
// The rest is just setup stuff, to make the area scrollable.
for( var i=0; i<100; i++ ){
$('ul').append('<li class="inview">List item '+i+'</li>');
}
$(window).trigger('resize.measure');
})
You can get window's visible area by,
var pwidth = $(window).width();
var pheight = $(window).height();
Then get document scroll,
$(document).scroll(function(e) {
var top = $(this).scrollTop();
$("h1").html("total visible area is from:"+ top +" to "+ (pheight + top) +"px");
});
Full example is here : http://jsfiddle.net/parag1111/kSaNp/
I want to know how to get the X and Y position of HTML elements such as img and div in JavaScript.
The correct approach is to use element.getBoundingClientRect():
var rect = element.getBoundingClientRect();
console.log(rect.top, rect.right, rect.bottom, rect.left);
Internet Explorer has supported this since as long as you are likely to care about and it was finally standardized in CSSOM Views. All other browsers adopted it a long time ago.
Some browsers also return height and width properties, though this is non-standard. If you're worried about older browser compatibility, check this answer's revisions for an optimised degrading implementation.
The values returned by element.getBoundingClientRect() are relative to the viewport. If you need it relative to another element, simply subtract one rectangle from the other:
var bodyRect = document.body.getBoundingClientRect(),
elemRect = element.getBoundingClientRect(),
offset = elemRect.top - bodyRect.top;
alert('Element is ' + offset + ' vertical pixels from <body>');
This function returns an element's position relative to the whole document (page):
function getOffset(el) {
const rect = el.getBoundingClientRect();
return {
left: rect.left + window.scrollX,
top: rect.top + window.scrollY
};
}
Using this we can get the X position:
getOffset(element).left
... or the Y position:
getOffset(element).top
The libraries go to some lengths to get accurate offsets for an element.
here's a simple function that does the job in every circumstances that I've tried.
function getOffset( el ) {
var _x = 0;
var _y = 0;
while( el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) ) {
_x += el.offsetLeft - el.scrollLeft;
_y += el.offsetTop - el.scrollTop;
el = el.offsetParent;
}
return { top: _y, left: _x };
}
var x = getOffset( document.getElementById('yourElId') ).left;
If you want it done only in javascript, here are some one liners using getBoundingClientRect()
window.scrollY + document.querySelector('#elementId').getBoundingClientRect().top // Y
window.scrollX + document.querySelector('#elementId').getBoundingClientRect().left // X
The first line will return offsetTop say Y relative to document.
The second line will return offsetLeft say X relative to document.
getBoundingClientRect() is a javascript function that returns the position of the element relative to viewport of window.
HTML elements on most browsers will have:-
offsetLeft
offsetTop
These specifiy the position of the element relative its nearest parent that has layout. This parent can often be accessed bif the offsetParent property.
IE and FF3 have
clientLeft
clientTop
These properties are less common, they specify an elements position with its parents client area (padded area is part of the client area but border and margin is not).
If page includes - at least- any "DIV", the function given by meouw throws the "Y" value beyond current page limits. In order to find the exact position, you need to handle both offsetParent's and parentNode's.
Try the code given below (it is checked for FF2):
var getAbsPosition = function(el){
var el2 = el;
var curtop = 0;
var curleft = 0;
if (document.getElementById || document.all) {
do {
curleft += el.offsetLeft-el.scrollLeft;
curtop += el.offsetTop-el.scrollTop;
el = el.offsetParent;
el2 = el2.parentNode;
while (el2 != el) {
curleft -= el2.scrollLeft;
curtop -= el2.scrollTop;
el2 = el2.parentNode;
}
} while (el.offsetParent);
} else if (document.layers) {
curtop += el.y;
curleft += el.x;
}
return [curtop, curleft];
};
You can add two properties to Element.prototype to get the top/left of any element.
Object.defineProperty( Element.prototype, 'documentOffsetTop', {
get: function () {
return this.offsetTop + ( this.offsetParent ? this.offsetParent.documentOffsetTop : 0 );
}
} );
Object.defineProperty( Element.prototype, 'documentOffsetLeft', {
get: function () {
return this.offsetLeft + ( this.offsetParent ? this.offsetParent.documentOffsetLeft : 0 );
}
} );
This is called like this:
var x = document.getElementById( 'myDiv' ).documentOffsetLeft;
Here's a demo comparing the results to jQuery's offset().top and .left: http://jsfiddle.net/ThinkingStiff/3G7EZ/
To retrieve the position relative to the page efficiently, and without using a recursive function: (includes IE also)
var element = document.getElementById('elementId'); //replace elementId with your element's Id.
var rect = element.getBoundingClientRect();
var elementLeft,elementTop; //x and y
var scrollTop = document.documentElement.scrollTop?
document.documentElement.scrollTop:document.body.scrollTop;
var scrollLeft = document.documentElement.scrollLeft?
document.documentElement.scrollLeft:document.body.scrollLeft;
elementTop = rect.top+scrollTop;
elementLeft = rect.left+scrollLeft;
How about something like this, by passing ID of the element and it will return the left or top, we can also combine them:
1) find left
function findLeft(element) {
var rec = document.getElementById(element).getBoundingClientRect();
return rec.left + window.scrollX;
} //call it like findLeft('#header');
2) find top
function findTop(element) {
var rec = document.getElementById(element).getBoundingClientRect();
return rec.top + window.scrollY;
} //call it like findTop('#header');
or 3) find left and top together
function findTopLeft(element) {
var rec = document.getElementById(element).getBoundingClientRect();
return {top: rec.top + window.scrollY, left: rec.left + window.scrollX};
} //call it like findTopLeft('#header');
Here's a modern 1-liner using vanilla JS to recursively iterate over element.offsetTop and element.offsetParent:
Function:
getTop = el => el.offsetTop + (el.offsetParent && getTop(el.offsetParent))
Usage:
const el = document.querySelector('#div_id');
const elTop = getTop(el)
Advantage:
Always returns the absolute vertical offset, regardless of the current scroll position.
Traditional syntax:
function getTop(el) {
return el.offsetTop + (el.offsetParent && getTop(el.offsetParent));
}
jQuery .offset() will get the current coordinates of the first element, or set the coordinates of every element, in the set of matched elements, relative to the document.
Update:
The recursion approach (in my old answer) creates many call stacks. We can use a while loop to avoid recursion in this case:
/**
*
* #param {HTMLElement} el
* #return {{top: number, left: number}}
*/
function getDocumentOffsetPosition(el) {
let top = 0, left = 0;
while (el !== null) {
top += el.offsetTop;
left += el.offsetLeft;
el = el.offsetParent;
}
return {top, left};
}
Old answer:
/**
*
* #param {HTMLElement} el
* #return {{top: number, left: number}}
*/
function getDocumentOffsetPosition(el) {
var position = {
top: el.offsetTop,
left: el.offsetLeft
};
if (el.offsetParent) {
var parentPosition = getDocumentOffsetPosition(el.offsetParent);
position.top += parentPosition.top;
position.left += parentPosition.left;
}
return position;
}
Thank ThinkingStiff for the answer, this is only another version.
You might be better served by using a JavaScript framework, that has functions to return such information (and so much more!) in a browser-independant fashion. Here are a few:
Prototype
jQuery
MooTools
YUI (yahoo)
With these frameworks, you could do something like:
$('id-of-img').top
to get the y-pixel coordinate of the image.
I've taken #meouw's answer, added in the clientLeft that allows for the border, and then created three versions:
getAbsoluteOffsetFromBody - similar to #meouw's, this gets the absolute position relative to the body or html element of the document (depending on quirks mode)
getAbsoluteOffsetFromGivenElement - returns the absolute position relative to the given element (relativeEl). Note that the given element must contain the element el, or this will behave the same as getAbsoluteOffsetFromBody. This is useful if you have two elements contained within another (known) element (optionally several nodes up the node tree) and want to make them the same position.
getAbsoluteOffsetFromRelative - returns the absolute position relative to the first parent element with position: relative. This is similar to getAbsoluteOffsetFromGivenElement, for the same reason but will only go as far as the first matching element.
getAbsoluteOffsetFromBody = function( el )
{ // finds the offset of el from the body or html element
var _x = 0;
var _y = 0;
while( el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) )
{
_x += el.offsetLeft - el.scrollLeft + el.clientLeft;
_y += el.offsetTop - el.scrollTop + el.clientTop;
el = el.offsetParent;
}
return { top: _y, left: _x };
}
getAbsoluteOffsetFromGivenElement = function( el, relativeEl )
{ // finds the offset of el from relativeEl
var _x = 0;
var _y = 0;
while( el && el != relativeEl && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) )
{
_x += el.offsetLeft - el.scrollLeft + el.clientLeft;
_y += el.offsetTop - el.scrollTop + el.clientTop;
el = el.offsetParent;
}
return { top: _y, left: _x };
}
getAbsoluteOffsetFromRelative = function( el )
{ // finds the offset of el from the first parent with position: relative
var _x = 0;
var _y = 0;
while( el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) )
{
_x += el.offsetLeft - el.scrollLeft + el.clientLeft;
_y += el.offsetTop - el.scrollTop + el.clientTop;
el = el.offsetParent;
if (el != null)
{
if (getComputedStyle !== 'undefined')
valString = getComputedStyle(el, null).getPropertyValue('position');
else
valString = el.currentStyle['position'];
if (valString === "relative")
el = null;
}
}
return { top: _y, left: _x };
}
If you are still having problems, particularly relating to scrolling, you could try looking at http://www.greywyvern.com/?post=331 - I noticed at least one piece of questionable code in getStyle which should be fine assuming browsers behave, but haven't tested the rest at all.
Difference between small and little
function getPosition( el ) {
var x = 0;
var y = 0;
while( el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) ) {
x += el.offsetLeft - el.scrollLeft;
y += el.offsetTop - el.scrollTop;
el = el.offsetParent;
}
return { top: y, left: x };
}
Look a example coordinates:
http://javascript.info/tutorial/coordinates
If you are using jQuery, this could be a simple solution:
<script>
var el = $("#element");
var position = el.position();
console.log( "left: " + position.left + ", top: " + position.top );
</script>
if using jQuery, the dimensions plugin is excellent and allows you specify exactly what you want.
e.g.
Relative position, absolute position, absolute position without padding, with padding...
It goes on, let's just say there is a lot you can do with it.
Plus the bonus of using jQuery is it's lightweight file size and easy use, you won't go back to JavaScript without it afterwards.
The cleanest approach I have found is a simplified version of the technique used by jQuery's offset. Similar to some of the other answers it starts with getBoundingClientRect; it then uses the window and the documentElement to adjust for scroll position as well as things like the margin on the body (often the default).
var rect = el.getBoundingClientRect();
var docEl = document.documentElement;
var rectTop = rect.top + window.pageYOffset - docEl.clientTop;
var rectLeft = rect.left + window.pageXOffset - docEl.clientLeft;
var els = document.getElementsByTagName("div");
var docEl = document.documentElement;
for (var i = 0; i < els.length; i++) {
var rect = els[i].getBoundingClientRect();
var rectTop = rect.top + window.pageYOffset - docEl.clientTop;
var rectLeft = rect.left + window.pageXOffset - docEl.clientLeft;
els[i].innerHTML = "<b>" + rectLeft + ", " + rectTop + "</b>";
}
div {
width: 100px;
height: 100px;
background-color: red;
border: 1px solid black;
}
#rel {
position: relative;
left: 10px;
top: 10px;
}
#abs {
position: absolute;
top: 250px;
left: 250px;
}
<div id="rel"></div>
<div id="abs"></div>
<div></div>
To get the total offset of an element, you could recursively sum up all parent offsets:
function getParentOffset(el): number {
if (el.offsetParent) {
return el.offsetParent.offsetTop + getParentOffset(el.offsetParent);
} else {
return 0;
}
}
with this utility function the total top offset of a dom element is:
el.offsetTop + getParentOffset(el);
This is the best code I've managed to create (works in iframes as well, unlike jQuery's offset()). Seems webkit has a bit of a different behavior.
Based on meouw's comment:
function getOffset( el ) {
var _x = 0;
var _y = 0;
while( el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) ) {
_x += el.offsetLeft - el.scrollLeft;
_y += el.offsetTop - el.scrollTop;
// chrome/safari
if ($.browser.webkit) {
el = el.parentNode;
} else {
// firefox/IE
el = el.offsetParent;
}
}
return { top: _y, left: _x };
}
While this is very likely to be lost at the bottom of so many answers, the top solutions here were not working for me.
As far as I could tell neither would any of the other answers have helped.
Situation:
In an HTML5 page I had a menu that was a nav element inside a header (not THE header but a header in another element).
I wanted the navigation to stick to the top once a user scrolled to it, but previous to this the header was absolute positioned (so I could have it overlay something else slightly).
The solutions above never triggered a change because .offsetTop was not going to change as this was an absolute positioned element. Additionally the .scrollTop property was simply the top of the top most element... that is to say 0 and always would be 0.
Any tests I performed utilizing these two (and same with getBoundingClientRect results) would not tell me if the top of the navigation bar ever scrolled to the top of the viewable page (again, as reported in console, they simply stayed the same numbers while scrolling occurred).
Solution
The solution for me was utilizing
window.visualViewport.pageTop
The value of the pageTop property reflects the viewable section of the screen, therefore allowing me to track where an element is in reference to the boundaries of the viewable area.
Probably unnecessary to say, anytime I am dealing with scrolling I expect to use this solution to programatically respond to movement of elements being scrolled.
Hope it helps someone else.
IMPORTANT NOTE: This appears to work in Chrome and Opera currently & definitely not in Firefox (6-2018)... until Firefox supports visualViewport I recommend NOT using this method, (and I hope they do soon... it makes a lot more sense than the rest).
UPDATE:
Just a note regarding this solution. While I still find what I discovered to be very valuable for situations in which "...programmatically respond to movement of elements being scrolled." is applicable. The better solution for the problem that I had was to use CSS to set position: sticky on the element. Using sticky you can have an element stay at the top without using javascript (NOTE: there are times this will not work as effectively as changing the element to fixed but for most uses the sticky approach will likely be superior)
UPDATE01:
So I realized that for a different page I had a requirement where I needed to detect the position of an element in a mildly complex scrolling setup (parallax plus elements that scroll past as part of a message).
I realized in that scenario that the following provided the value I utilized to determine when to do something:
let bodyElement = document.getElementsByTagName('body')[0];
let elementToTrack = bodyElement.querySelector('.trackme');
trackedObjPos = elementToTrack.getBoundingClientRect().top;
if(trackedObjPos > 264)
{
bodyElement.style.cssText = '';
}
Hope this answer is more widely useful now.
I did it like this so it was cross-compatible with old browsers.
// For really old browser's or incompatible ones
function getOffsetSum(elem) {
var top = 0,
left = 0,
bottom = 0,
right = 0
var width = elem.offsetWidth;
var height = elem.offsetHeight;
while (elem) {
top += elem.offsetTop;
left += elem.offsetLeft;
elem = elem.offsetParent;
}
right = left + width;
bottom = top + height;
return {
top: top,
left: left,
bottom: bottom,
right: right,
}
}
function getOffsetRect(elem) {
var box = elem.getBoundingClientRect();
var body = document.body;
var docElem = document.documentElement;
var scrollTop = window.pageYOffset || docElem.scrollTop || body.scrollTop;
var scrollLeft = window.pageXOffset || docElem.scrollLeft || body.scrollLeft;
var clientTop = docElem.clientTop;
var clientLeft = docElem.clientLeft;
var top = box.top + scrollTop - clientTop;
var left = box.left + scrollLeft - clientLeft;
var bottom = top + (box.bottom - box.top);
var right = left + (box.right - box.left);
return {
top: Math.round(top),
left: Math.round(left),
bottom: Math.round(bottom),
right: Math.round(right),
}
}
function getOffset(elem) {
if (elem) {
if (elem.getBoundingClientRect) {
return getOffsetRect(elem);
} else { // old browser
return getOffsetSum(elem);
}
} else
return null;
}
More about coordinates in JavaScript here: http://javascript.info/tutorial/coordinates
HTML program to show (x, y) of an
element by dragging mouse over it you just copied it and use it on your own
<!DOCTYPE html>
<html>
<head>
<title>
position of an element
</title>
<!-- scropt to get position -->
<script type = "text/javascript">
function getPositionXY(element) {
var rect = element.getBoundingClientRect();
document.getElementById('text').innerHTML
= 'X: ' + rect.x + '<br>' + 'Y: ' + rect.y;
}
</script>
</head>
<body>
<p>Move the mouse over the text</p>
<div onmouseover = "getPositionXY(this)">
Position:
<p id = 'text'></p>
</div>
</body>
</html>
i could just like element.offsetLeft or element.offsetTop. Example :
document.getElementById('profileImg').offsetLeft
I successfully used Andy E's solution to position a bootstrap 2 modal depending on what link in a table row a user clicks on. The page is a Tapestry 5 page and javascript below is imported in the java page class.
javascript:
function setLinkPosition(clientId){
var bodyRect = document.body.getBoundingClientRect(),
elemRect = clientId.getBoundingClientRect(),
offset = elemRect.top - bodyRect.top;
offset = offset + 20;
$('#serviceLineModal').css("top", offset);
}
My modal code:
<div id="serviceLineModal" class="modal hide fade add-absolute-position" data-backdrop="static"
tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true" style="top:50%;">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-hidden="true">x</button>
<h3 id="myModalLabel">Modal header</h3>
</div>
<div class="modal-body">
<t:zone t:id="modalZone" id="modalZone">
<p>You selected service line number: ${serviceLineNumberSelected}</p>
</t:zone>
</div>
<div class="modal-footer">
<button class="btn" data-dismiss="modal" aria-hidden="true">Close</button>
<!-- <button class="btn btn-primary">Save changes</button> -->
</div>
The link in the loop:
<t:loop source="servicesToDisplay" value="service" encoder="encoder">
<tr style="border-right: 1px solid black;">
<td style="white-space:nowrap;" class="add-padding-left-and-right no-border">
<a t:type="eventLink" t:event="serviceLineNumberSelected" t:context="service.serviceLineNumber"
t:zone="pageZone" t:clientId="modalLink${service.serviceLineNumber}"
onmouseover="setLinkPosition(this);">
<i class="icon-chevron-down"></i> <!-- ${service.serviceLineNumber} -->
</a>
</td>
And the java code in the page class:
void onServiceLineNumberSelected(String number){
checkForNullSession();
serviceLineNumberSelected = number;
addOpenServiceLineDialogCommand();
ajaxResponseRenderer.addRender(modalZone);
}
protected void addOpenServiceLineDialogCommand() {
ajaxResponseRenderer.addCallback(new JavaScriptCallback() {
#Override
public void run(JavaScriptSupport javascriptSupport) {
javascriptSupport.addScript("$('#serviceLineModal').modal('show');");
}
});
}
Hope this helps someone, this post helped out.
After much research and testing this seems to work
function getPosition(e) {
var isNotFirefox = (navigator.userAgent.toLowerCase().indexOf('firefox') == -1);
var x = 0, y = 0;
while (e) {
x += e.offsetLeft - e.scrollLeft + (isNotFirefox ? e.clientLeft : 0);
y += e.offsetTop - e.scrollTop + (isNotFirefox ? e.clientTop : 0);
e = e.offsetParent;
}
return { x: x + window.scrollX, y: y + window.scrollY };
}
see http://jsbin.com/xuvovalifo/edit?html,js,output
Just thought I'd throw this out there as well.
I haven't been able to test it in older browsers, but it works in the latest of the top 3. :)
Element.prototype.getOffsetTop = function() {
return ( this.parentElement )? this.offsetTop + this.parentElement.getOffsetTop(): this.offsetTop;
};
Element.prototype.getOffsetLeft = function() {
return ( this.parentElement )? this.offsetLeft + this.parentElement.getOffsetLeft(): this.offsetLeft;
};
Element.prototype.getOffset = function() {
return {'left':this.getOffsetLeft(),'top':this.getOffsetTop()};
};
This is easy as two lines in JS :
var elem = document.getElementById("id");
alert(elem.getBoundingClientRect());
Since different browsers are rendering border, padding, margin and etc in different way. I wrote a little function to retrieve top and left positions of specific element in every root element that you want in precise dimension:
function getTop(root, offset) {
var rootRect = root.getBoundingClientRect();
var offsetRect = offset.getBoundingClientRect();
return offsetRect.top - rootRect.top;
}
For retrieve left position you must return:
return offsetRect.left - rootRect.left;
Get position of div in respect to left and Top
var elm = $('#div_id'); //get the div
var posY_top = elm.offset().top; //get the position from top
var posX_left = elm.offset().left; //get the position from left