Develop Reference

Scroll function doesnt work after using some elements

Im using a scroll function this works perfect whenever I use normal text for it, but whenever I use Text<br>Text<p> it wont scroll automaticly because there is a<p> or <br> what to do to make it also scroll for once with other elements.
And is there a simple way to use it for all $('#scrollDiv') istead of copy paste it above every line?
Example usage:
//This scrolls correct
$('#scrollDiv').append('Hello world!');
scrollDiv($('.scroll-text:eq(0)'));
//This wont work scrolling
$('#scrollDiv').append('Hello<br>world!');
scrollDiv($('.scroll-text:eq(0)'));
//This also wont work
$('#scrollDiv').append('<span style="font-size:100px;">Hello</span>');
scrollDiv($('.scroll-text:eq(0)'));
function scrollDiv($div, h){
var scrollHeight = $div[0].scrollHeight;
var scrollTop = $div[0].scrollTop;
var height = $div[0].clientHeight;
var h_invisible = scrollHeight - scrollTop - height;
if(h){
if(h>h_invisible){
$div.scrollTop(1e5);
}
}else{
if(15>h_invisible){
$div.scrollTop(1e5);
}
}
}

scrollDiv($('.scroll-text:eq(0)'), 50);
could help you out..

document.body.scrollTop value stuck at 0

I have a bit of text that I want to change when the user scrolls a certain distance. However, when I scroll, the value of document.body.scrollTop remains at 0.
var scroll = document.body.scrollTop;
if (scroll < 50) {
document.write("A");
} else {
document.write("B");
}
When checking the log, the value of scroll never budges from 0, thus the text never switches from A to B when scrolling. Thanks for any help in advance.
EDIT: None of the first three answers seem to work for me. I suppose I should provide some context.
Building my design portfolio site. View the early build here. I'd like to be able to change the word "designer" in the banner to other descriptor words as the user scrolls down the page, but can't seem to be able to listen to the current scroll location.

Why are you placing that script inline within the banner? Why not implement your logic within your existing $(window).scroll(function () { as that event seems to be setting the opacity correctly on scroll.
Just add:
if(scrollTop < 50){
$('#banner h1').text("My name is John. I'm a designer");
} else {
$('#banner h1').text("My name is John. I'm a thinker");
}
Live Demo
if(document.attachEvent){
document.attachEvent('onscroll', scrollEvent);
}else if(document.addEventListener){
document.addEventListener('scroll', scrollEvent, false);
}
function scrollEvent(e){
var scroll = document.body.scrollTop;
var text = null;
if (scroll < 50) {
text = document.createTextNode('A');
} else {
text = document.createTextNode('B');
}
document.body.appendChild(text);
}
Though unrelated to your issue, you should stay away from document.write whenever you can. See Why is document.write considered a "bad practice"? for more detail.

this should do it. "document.documentElement.scrollTop" is an IE variant.
should work cross browsers.
window.onscroll = function() {
var scroll = window.scrollY || document.documentElement.scrollTop;
if (scroll < 50) {
document.write("A");
} else {
document.write("B");
}
}

DEMO FIDDLE
var el = $('.test');
//alert(el.scrollTop());
el.on('scroll', function(){
if(el.scrollTop()>50){
alert(el.scrollTop());
}
});
Try this.

Jquery when the user hits bottom of the page

I've been working on a scroll to top function for my website, and that part of it works fine. My problem is however that I have a fixed div that is overlapping my footer when it hits the bottom of the page.
Here is the function that I have working.
$(document).scroll(function (e) {
if (document.body.scrollTop >= 800) {
$('#beamUp').show(1000);
} else {
$('#beamUp').hide(1000);
return false;
}
});
Is there somehow I could detect when I hit that part of the page and stop the div from moving past that.Help is much appreciated!
jsFiddle: http://jsfiddle.net/zazvorniki/RTDpw/

Just get the height of the page, minus the height of the div in question, as well as the footer... make sure the top is never greater than that value... you'll also need an onresize event handler re-evaluate that value.
looking at your jsfiddle... here are my edits
In your scroll listener, I am checking for the position of the page, and adjusting the bottom position of the floater appropriately. I also set the initial display:none, so you don't need to call .hide() in your initial script. In addition, resizing the window has the effect of scrolling for your use, so I changed the listener for both events.
$(document).on('scroll resize', function (e) {
var viewHeight = $(window).height();
var viewTop = $(window).scrollTop();
var footerTop = $("footer").offset().top;
var baseline = (viewHeight + viewTop) - footerTop;
var bu = $("#beamUp").css({bottom: (baseline < 0 ? 0 : baseline) + 'px'});
if (viewTop >= 50) {
bu.show(1000);
} else {
bu.hide(1000);
}
});

Getting Coordinates of an element on page scroll

I am having this problem where i have a set of 6 UL's having a common class x.Each of them consist of a specific section of the page.Now i have 6 menus that are related to each of the section.What i have to do is highlight the menu when its related section is in users view.
For this i thought that may be jQuery position(); or offset(); could have helped but they give the top and left of the element.I also tried using jQuery viewport plugin but apparently view port is big it can show more than one UL at a time hence i cant apply element specific logic here.I am not familliar to this but does anything changes of an element on scrolling?If yes then how to access it?
Please share your views.
Regards
Himanshu Sharma.

Is very easy to do it using jQuery and a dummy fixed HTML block that helps you find the current position of the viewport.
$(window).on("scroll load",function(){
var once = true;
$(".title").each(function(ele, index){
if($(this).offset().top > $("#viewport_helper").offset().top && once){
var index = $(this).index(".title");
$(".current").removeClass('current')
$("#menu li").eq(index).addClass('current')
once = false;
}
});
})
Check out a working example: http://jsfiddle.net/6c8Az/1/
You could also do something similar with the jQuery plugin, together with the :first selector:
$(window).on("scroll load",function(){
$(".title:in-viewport:first").each(function(){
var index = $(this).index(".title");
$(".current").removeClass('current')
$("#menu li").eq(index).addClass('current')
});
})

You can get the viewport's width and height via $(document).width() and $(document).height()
You can get how many pixels user scrolls via $(document).scrollTop() and $(document).scrollLeft
Combining 1 and 2, you can calculate where the viewport rectangle is
You can get the rectangle of an element using $(element).offset(), $(element).width() and $(element).height()
So the only thing left to you is to determine whether the viewport's rectangle contains (or interacts) the elements's rectangle
So the whole code may look like:
/**
* Check wether outer contains inner
* You can change this logic to matches what you need
*/
function rectContains(outer, inner) {
return outer.top <= inner.top &&
outer.bottom >= inner.bottom &&
outer.left <= inner.left &&
outer.right >= inner.right;
}
/**
* Use this function to find the menu related to <ul> element
*/
function findRelatedMenu(element) {
return $('#menu-' + element.attr('id'));
}
function whenScroll() {
var doc = $(document);
var elem = $(element);
var viewportRect = {
top: doc.scrollTop(),
left: doc.scrollLeft(),
width: doc.width(),
height: doc.height()
};
viewportRect.bottom = viewportRect.top + viewportRect.height;
viewportRect.right = viewportRect.left + viewportRect.width;
var elements = $('ul.your-class');
for (var i = 0; i < elements.length; i++) {
var elem = $(elements[i]);
var elementRect = {
top: elem.offset().top,
left: elem.offset().left,
width: elem.width(),
height: elem.height()
};
elementRect.bottom = elementRect.top + elementRect.height;
elementRect.right = elementRect.left + elementRect.width;
if (rectContains(viewportRect, elementRect)) {
findRelatedMenu(elem).addClass('highlight');
}
}
}
$(window).on('scroll', whenScroll);

Let's see if i understood well. You have a page long enough to scroll, and there is an element that when it appears in the viewport, you wanna do something with it. So the only event that's is triggered for sure on the time the element gets in the viewport is the 'scroll'. So if the element is on the page and the scroll is on the viewport, what you need to do is bind an action to the scroll event to check if the element is in the view each time the event is trigger. Pretty much like this:
$(window).scroll(function() {
check_element_position();
});
Now, in order for you to know if the element is in the viewport, you need 3 things. The offset top of that element, the size of the viewport and the scroll top of the window. Should pretty much look like this:
function check_element_position() {
var win = $(window);
var window_height = win.height();
var element = $(your_element);
var elem_offset_top = element.offset().top;
var elem_height = element.height();
var win_scroll = win.scrollTop();
var pseudo_offset = (elem_offset_top - win_scroll);
if (pseudo_offset < window_height && pseudo_offset >= 0) {
// element in view
}
else {
// elem not in view
}
}
Here, (elem_offset_top - win_scroll) represent the element position if there was no scroll. Like this, you just have to check if the element offset top is higher then the window viewport to see if it's in view or not.
Finally, you could be more precise on you calculations by adding the element height (variable already in there) because the code i just did will fire the event even if the element is visible by only 1 pixels.
Note: I just did that in five minutes so you might have to fix some of this, but this gives you a pretty darn good idea of what's going on ;)
Feel free to comment and ask questions

What is different with window and div widths between firefox and IE

I have a web page that uses a scrolling div to display table information. When the window is resized (and also on page load), the display is centered and the div's scrollbar positioned to the right of the page by setting its width. For some reason, the behaviour is different under firefox than IE. IE positions/sizes the div as expected, but firefox seems to make it too wide, such that the scrollbar begins to disappear when the window client width reaches about 800px. I'm using the following methods to set the position and size:
function getWindowWidth() {
var windowWidth = 0;
if (typeof(window.innerWidth) == 'number') {
windowWidth=window.innerWidth;
}
else {
if (document.documentElement && document.documentElement.clientWidth) {
windowWidth=document.documentElement.clientWidth ;
}
else {
if (document.body && document.body.clientWidth) {
windowWidth=document.body.clientWidth;
}
}
}
return windowWidth;
}
function findLPos(obj) {
var curleft = 0;
if (obj.offsetParent) {
curleft = obj.offsetLeft
while (obj = obj.offsetParent) {
curleft += obj.offsetLeft
}
}
return curleft;
}
var bdydiv;
var coldiv;
document.body.style.overflow="hidden";
window.onload=resizeDivs;
window.onresize=resizeDivs;
function resizeDivs(){
bdydiv=document.getElementById('bdydiv');
coldiv=document.getElementById('coldiv');
var winWdth=getWindowWidth();
var rghtMarg = 0;
var colHdrTbl=document.getElementById('colHdrTbl');
rghtMarg = parseInt((winWdth - 766) / 2) - 8;
rghtMarg = (rghtMarg > 0 ? rghtMarg : 0);
coldiv.style.paddingLeft = rghtMarg + "px";
bdydiv.style.paddingLeft = rghtMarg + "px";
var bdydivLft=findLPos(bdydiv);
if ((winWdth - bdydivLft) >= 1){
bdydiv.style.width = winWdth - bdydivLft;
coldiv.style.width = bdydiv.style.width;
}
syncScroll();
}
function syncScroll(){
if(coldiv.scrollLeft>=0){
coldiv.scrollLeft=bdydiv.scrollLeft;
}
}
Note that I've cut out other code which sets height, and other non-relevant parts. The full page can be seen here. If you go to the link in both IE and firefox, resize width until "800" is displayed in the green box top-right, and resize height until the scrollbar at the right is enabled, you can see the problem. If you then resize the IE width, the scrollbar stays, but if you resize the firefox width wider, the scrollbar begins to disappear. I'm at a loss as to why this is happening....
Note that AFAIK, getWindowWidth() should be cross-browser-compatible, but I'm not so sure about findLPos().... perhaps there's an extra object in Firefox's DOM or something, which is changing the result??

You are dealing with "one of the best-known software bugs in a popular implementation of Cascading Style Sheets (CSS)" according to Wikipedia. I recommend the Element dimensions and CSS Object Model View pages on Quirksmode.org.
Also: I think you'll find that Safari and Opera behave like Firefox in most circumstances. A more compatible approach to working around these problems is testing for, and making exceptions for, MSIE instead of the other way around.

Ok, I found the problem. Seems to be that firefox does not include the style.paddingLeft value in its style.width setting, whereas IE does, thus the div was ending up exactly style.paddingLeft too wide. That is, if for example style.paddingLeft is 8, IE's style.width value would be 8 more than FireFox's - and thus the inverse when setting the value, for FireFox I needed to subtract the style.paddingLeft value
Modified code with:
if (__isFireFox){
bdydiv.style.width = winWdth - bdydivLft - rghtMarg;
} else {
bdydiv.style.width = winWdth - bdydivLft;
}

As long as you don't include a valid doctype, you can't expect consistent results, due to Quirks Mode. Go add one (HTML 4.01 Transitional is fine), then let us know if it still occurs.
Also see http://en.wikipedia.org/wiki/Quirks_mode.

In your getWindowWidth() function, whenever you grab the width of something, instead of this:
windowWidth = document.documentElement.clientWidth;
try this
windowWidth = Math.max(document.documentElement.scrollWidth, document.documentElement.clientWidth);

A detail to help optimize some of your code:
function getPos(elm) {//jumper
for(var zx=zy=0;elm!=null;zx+=elm.offsetLeft,zy+=elm.offsetTop,elm=elm.offsetParent);
return {x:zx,y:zy}
}
(jumper is a user who posted this code in Eksperten.dk)