document.body.scrollTop value stuck at 0 - javascript

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.

Related

How to make an element become fixed when 50px from the top of the screen

I have a html div element that scrolls with the page but I would like it to become fixed once it reaches 50px from the top of the screen...
How is this done?
My div id is #box
Thanks!
-Ina
If you want it to be fixed at the top of the page at some distance from the top, you can check the top offset of the element and change the class when it reach the distance you want.
Here is the jquery code for your reference
jQuery(document).scroll(function() {
var documentTop = jQuery(document).scrollTop();
console.log('this is current top of your document' + documentTop );
//box top is 891
if (documentTop > 841) {
//change the value of the css at this point
jQuery("#box").addClass("stayfix");
}
else
{
jQuery("#box").removeClass("stayfix");
}
});
You need to be more specific about what have you done so far. For eg, how did you make the div element to scrolls inside the page. using css or js/jquery animation features?That will help us to give more specific answer.
**Edited According to your fiddle.
They are right, this question is duplicate. Here is a code I made with answers from the forum.
var box_top = $("#box").offset().top;
$(window).scroll(function (event) {
if ($(window).scrollTop() >= (box_top - 50)) {
$("#box").css({position:"fixed",top:"50px"});
} else {
$("#box").css({position:"relative"});
}
});
Hope it helps anyway.
https://jsfiddle.net/ay54msd5/1/
Try something like this. It's a solution using jquery (hopefully not a problem) that checks the scrollHeight of the page every time the page scrolls. If the scrollHeight is greater than a certain threshold, the element becomes fixed. If not, the element is positioned relatively (but you can do whatever you want in that case.
$(document).ready(function() {
var navFixed = false;
var $box = $("#box");
var topHeight = 50;
$(document).scroll(function() {
if ($(document).scrollTop() >= topHeight && !navFixed) {
$box.css("position", "fixed");
navFixed = true;
}
else if ($(document).scrollTop() < topHeight && navFixed) {
$box.css("position", "relative");
navFixed = false;
}
});
});
You would have to write some additional CSS targeting the #box element that tells it what coordinates you'd like it to be fixed to.

Having the same nav bar become fixed after scrolling past a certain element

I currently have a nav bar within my header that I would like to become fixed after the user scrolls past a certain element. I would also like to achieve the same animation effect as seen at http://pixelmatters.com
When I say 'same' I mean using the same nav bar/header element that I'm using at the top, rather than using a duplicate somewhere else in my document.
I've tried to achieve he result with my own code shown below. I've also included a jsFiddle link of my current setup.
jQuery
var bottomElement = $('.dividerWrap').offset().top + $('.dividerWrap').height();
$(window).on('scoll', function() {
var stop = Math.round($(window).scrollTop());
if (stop > bottomElement) {
$('.header').addClass('isFixed');
} else {
$('.header').removeClass('isFixed');
}
});
https://jsfiddle.net/npfc8wsx/1/
I answered something like that few days ago. please take a look at this code:
$(window).scroll(function () {
var scrollTop = $(window).scrollTop();
var scrollToVid = $('#test').offset().top
console.log(scrollTop); //see window scroll distance //
console.log(scrollToVid); //see scroll to div offest//
if ($(window).scrollTop() >= scrollToVid) {
alert('You reached to the video!');
}
});
jSFiddle
Main Question
now for you some code must change:
$(window).scroll(function () {
var scrollToElem = $('.dividerWrap').offset().top
if ($(window).scrollTop() >= scrollToElem) {
$('.header').addClass('isFixed');
} else {
$('.header').removeClass('isFixed');
}
});

Remove class if other class present at scroll height

I need to hide an element on scroll - but only if its not already hidden.
I've written the following jQuery but it's not working for some reason - any tips please?
The css class open-style-switcher and close-style-switcher determine a css scroll anim. I want to wait until the page has scrolled to a certain height, then auto hide the search box if it contains the open class.
Where am I going wrong!?
$(window).scroll(function() {
var scroll = $(window).scrollTop();
if (scroll >= 500) {
$('#search-box').hasClass('open-style-switcher').toggleClass("open-style-switcher", "close-style-switcher", 1000);
}
});
"toggleClass" can receive two classes separated by space
Also creating "$searchBox" variable to avoid double search in DOM.
And as was told before: hasClass() returns boolean
Here it is:
$(window).scroll(function() {
var scroll = $(window).scrollTop();
if (scroll >= 500) {
var $searchBox = $('#search-box');
if ($searchBox.hasClass('open-style-switcher'))
{
$searchBox.toggleClass("open-style-switcher close-style-switcher", 1000);
}
}
});
.hasClass() - Returns: Boolean determines whether any of the matched elements are assigned the given class.
In your scenario, addClass and removeClass is more suitable.
See below :
$(window).scroll(function() {
var scroll = $(window).scrollTop();
var searchbox = $('#search-box');
if (scroll >= 500 && searchbox.hasClass('open-style-switcher')) {
searchbox.removeClass("open-style-switcher");
searchbox.addClass("close-style-switcher", 1000);
}
});
toggleClass() does not work in the way you, or even the other answers, think it does. It only adds and removes classes, not exchange them for others. See toggleClass() documentation here.
if (scroll >= 500) {
if($('#search-box').hasClass('open-style-switcher'))
{
$('#search-box').removeClass("open-style-switcher");
$('#search-box').addClass("close-style-switcher");
}
}
I imagine you will also want an else block that does the inverse of this. Perhaps the below is a more straight forward way of doing what you want to achieve as there may not be any point in the check to see if the #search-box already has the open-style-switcher class.
if (scroll >= 500) {
$('#search-box').removeClass("open-style-switcher").addClass("close-style-switcher");
}
else
{
$('#search-box').removeClass("close-style-switcher").addClass("open-style-switcher");
}

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);
}
});

How to add css to a div once it hits the top of the page (when scrolling)?

I would like to make it so when user scrolls down and reaches a certain div, say #float, set that div to margin-top: 50px and position fixed, and if user scrolls back up undo those changes. It's hard to understand I know ))) If you go to this page and pay your attention to sidebar once scrolling up and down you will see what I mean.
As you scroll down 2nd advertisement scrolls with a page too.
How would I achieve same functionality with jQuery/CSS?
This is a way of doing it in jQuery.
This code is provided for example purposes only; there are almost certainly a handful of regularly-maintained jQuery plugins that will do this thing for you - check GitHub or DailyJS.
$(window).scroll(function() {
var styledDiv = $('#styledDiv'),
targetScroll = $('#float').position().top,
currentScroll = $('html').scrollTop() || $('body').scrollTop();
styledDiv.toggleClass('fixedPos', currentScroll >= targetScroll);
});
Here is a simple JSFiddle of the above in action.
Edit: Have now refactored this code to a more elegant solution.
Edit 2: Following an email I received about a question, I've updated the code above so that it also works in Firefox. As $('body').scrollTop() will not work in Firefox (See comments on the jQuery API page), we need to check both the html and body elements.
This is the relevant jQuery/JavaScript code use on that site.
if (window.XMLHttpRequest) {
var topGagStay = $("top-gag-stay");
var isLoggedIn = $("profile-menu") ? true : false;
var sidebarAdsTop = 1061 - 545;
var signupBtnOffset = 60;
var dockPos = 72;
if (!isLoggedIn && !GAG.isReadOnly()) {
sidebarAdsTop += signupBtnOffset
}
if (formMessageShown) {
sidebarAdsTop += formMessageOffset
}
if (topGagStay) {
if (document.documentElement.scrollTop > sidebarAdsTop || self.pageYOffset > sidebarAdsTop) {
if (topGagStay.style.position != "fixed") {
topGagStay.style.position = "fixed";
topGagStay.style.top = dockPos + "px"
}
} else {
if (document.documentElement.scrollTop < sidebarAdsTop || self.pageYOffset < sidebarAdsTop) {
topGagStay.style.position = "";
topGagStay.style.top = ""
}
}
}
}
Thank FireBug and http://jsbeautifier.org/ for the code (and 9GAG, of course).
I have tried the above answer by beardtwizzle and it worked fine. Also made it work for the case when the page is scrolled upto the bottom of the page.
see the working demo/tutorial here

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