Adding offset().top amount on scroll - javascript

I have a fixed piece of text and I'm trying to add a different class each time the text enters a div on scroll. I've got it working no problem. But if I add an offset amount to the fixed text e.g.
top: 400px
I need to counter this offset in the JS. But I can't seem to figure it out. I've tried using:
.offset().top 400);
But it's not working. Here's a code i'm currently using:
HTML
<p class="text">TEXT HERE</p>
<div class="section1"></div>
<div class="section2"></div>
<div class="section3"></div>
<div class="section4"></div>
JS
$(window).scroll(function (event) {
var scroll = $(window).scrollTop();
$('.text').toggleClass('blue',
scroll >= $('.section1').offset().top
);
$('.text').toggleClass('magenta',
scroll >= $('.section2').offset().top
);
$('.text').toggleClass('green',
scroll >= $('.section3').offset().top
);
$('.text').toggleClass('orange',
scroll >= $('.section4').offset().top
);
});
//trigger the scroll
$(window).scroll();//ensure if you're in current position when page is refreshed
The text needs to add class as soon as it enters the relevant div.
Here's a working fiddle: http://jsfiddle.net/6PrQW/334/

So you did most everything right, but I think where you went wrong is here: var scroll = $(window).scrollTop();
You don't want to calculate using the window offset, rather you want to use the offset of your sticky text. So instead use: var scroll = $('.text').offset().top;
Let me know if that helps.
edit,
and here is your fiddle with the edits.
Note that I edited your line for setting the blue class since you don't want to match the sticky offset against itself.

To find out when something is within your window, you've gotta use something like...
if($(elem).offset().top - $(window).scrollTop < $(window).height()){
//stuff
}
That should trigger as soon as elem is visible on the page! You can check it against $(window).height()/2, for example, if you want it to trigger in the center of the page instead. Hope this helps!

Related

Scroll down one "scroll unit" on click

I want to create a link div which scrolls down on click; like one scroll down of the mouse wheel does or one click down on the arrow of the scroll bar.
Is there a method in CSS or jQuery/JavaScript to do that?
And also several scrolls, like 3 scroll downs?
Thanks for help!
As far as I know, there is no such thing as a scroll unit. This is device dependent.
But to make the window scroll when clicking something is simple with jQuery.
$(function(){
$(".clickScroll").click(function(e) {
document.body.scrollTop += 10;
});
});
This will scroll the view 10 units, of some measure, down on every click.
See this plunker for a full example.
You should try something like:
HTML
<div onclick="myFunction()"></div>
JavaScript
myFunction = function(){
var myVar = $(window).scrollTop();
$(window).scrollTop(myVar+300);
}
MyVar gets your position on the page.
I hope I've been helpful.

Add class to an element when user scrolls to 50px above it?

Does anyone know how I can achieve the following with jQuery:
I want to add a class (.fixed) to an element (#content) when a user reaches 50px above #content. And then, when the user scrolls up 50px above #content, I want to remove the class.
How can I do this with as little script as possible?
<div id="header">
</div>
<div id="content">
</div>
<div id="content-2">
</div>
FIDDLE
If I understand correctly, this should do the trick.
$(function(){
$(document).scroll(function(){
if($(this).scrollTop() >= $('#content').offset().top - 50) {
$("#content").css("background","red");
} else {
$("#content").css("background","orange");
}
});
});
Basically, it check the current position of the user's scroll and compare it to the position of the div minus 50 pixel.
If you just past this code in your document, it should work properly.
Try this,
$(window).scroll(function() {
if ($(this).scrollTop() > 50){
$('#content').addClass("content_fixed");
}
else{
$('#content').removeClass("content_fixed");
}
});
Demo : http://jsfiddle.net/UI_Designer/8j0a1Lkk/1/
You can use the jquery plugin waypoint (http://imakewebthings.com/waypoints/) to detect when the user has scrolled to the area and then use the javascript .innerhtml function to change the html code. The one problem with this method is that you have to have another element that surrounds your main element ONLY.

How to stick a div at the bottom of the page while scrolling after checkbox is checked

Usually I don't ask questions...I'm looking for a solution until I give up,
and this is the case here.
There are many similar questions to my but after a thorough search I found nothing.
So the question is:
After selecting a checkbox the div at the bottom of the page
shuold be sticky untill the user scrolling down to the original place where it was.
I have a great example from kickstarter web site :
If only I could know how they do it :)
If I was not clear enough I'd love to explain myself better.
Thanks in advance
After clicking on checkbox,
You can add these CSS lines to div
position:fixed;
bottom:0;
you want to add position: fixed and attach it to the bottom of the container when checked
html
<div class="wrapper">
<input type="checkbox" id="check"/>
<div id="foot"></div>
</div>
js
var check = document.getElementById('check');
var foot = document.getElementById('foot');
check.addEventListener('change', function () {
if (check.checked) {
foot.style.position = 'fixed';
foot.style.bottom = 0;
}
});
fiddle - http://jsfiddle.net/qak2ept6/
EDIT - http://jsfiddle.net/qak2ept6/1/ restore when unchecked
EDIT EDIT - http://jsfiddle.net/qak2ept6/3/ attach on scroll
when you check the check box. create div with position fixed and store the offset of the bottom edge of the window that would be normally your window height. Assign scroll event and keep checking if the scroll value is equal to the offset you have stored and when it reached just remove the fixed position from the div.
My guess (and if I was doing it) It'll be done by monitoring scroll position and applying a css style or not accordingly.
Something like
Inject it in invisible state in to the document
Note it's position (y coord)
Apply class to make it stick to the bottom of the window and show
On scroll, as soon as you get near the expected yCoord, remove the class and let it assume it's rightful place in the document
On further scroll (when you scroll away), re-apply class until you scroll back
HTH
If i have understood your question, I guess what you want is here
function sticky_relocate() {
var window_top = $(window).scrollTop();
var div_top = $('#sticky-anchor').offset().top
if (window_top > div_top) {
$('#sticky').addClass('stick');
} else {
$('#sticky').removeClass('stick');
}
}
$(function () {
$(window).scroll(sticky_relocate);
sticky_relocate();
});
If not, please explain us with more code and what exactly you need

Make a div appear when scrolling past a certain point of a page

My goal is to make a fixed div appear at the top of a page once someone scrolls a certain amount of pixels down the page. Basically once the header section is out of view, this div will appear.
I've looked at code similar to what I want; however, haven't seen anything that would allow me to easily modify the pixel count from the top of the page (if possible).
Here is a piece of code I saw dealing with making divs appear by scrolling.
// Get the headers position from the top of the page, plus its own height
var startY = $('header').position().top + $('header').outerHeight();
$(window).scroll(function(){
checkY();
});
function checkY(){
if( $(window).scrollTop() > startY ){
$('.fixedDiv').slideDown();
}else{
$('.fixedDiv').slideUp();
}
}
// Do this on load just in case the user starts half way down the page
checkY();
I just want to know how to make it appear. If someone knows of a piece of code already in tact with a slide up and slide down animation, that would be greatly appreciated as well but not required.
window.addEventListener("scroll",function() {
if(window.scrollY > 500) {
$('.fixedDiv').slideDown();
}
else {
$('.fixedDiv').slideUp();
}
},false);
Brandon Tilley answered my question in a comment...
You would change the first line, with the startY, to be the specific Y
position you need, rather than calculating based on the header's
position and height. Here's an updated fiddle:
jsfiddle.net/BinaryMuse/Ehney/1
window.addEventListener("scroll",function() {
$('.fixedDiv')[(window.scrollY > 500)?"slideDown":"slideUp"]();
},false);
DEMO: http://jsfiddle.net/DerekL/8eG2A/

How to make div appear from the top when scrolling down?

I would like a div to appear and slide down once you scroll pass the header.
Here's what it should look like:
http://www.space.com/11425-photos-supernovas-star-explosions.html
Here's what I got so far but it's not working.
http://jsfiddle.net/nHnrd/
You'll need to find out the height of the header and its position on the page then just show or hide the div depending on the scrollTop value using jquery.
For example:
// Get the headers position from the top of the page, plus its own height
var startY = $('header').position().top + $('header').outerHeight();
$(window).scroll(function(){
checkY();
});
function checkY(){
if( $(window).scrollTop() > startY ){
$('.fixedDiv').slideDown();
}else{
$('.fixedDiv').slideUp();
}
}
// Do this on load just in case the user starts half way down the page
checkY();
Then you'll just need to set the .fixedDiv to position:fixed: top: 0; left: 0;
Edit: I've added a checkY() function that you can call whenever the page loads as well as on scroll. To hide it initially though, just use CSS.
You might want to just show and hide your div rather than pseudo class AND hide and show
initially:
$("#mydiv").hide();
then (on scroll):
$("#mydiv").show();
set what you want your div to look like i.e. 0,0 and fixed
Use the Keep It Simple method!
I've updated your jsfiddle with something you can try.
Try this:
http://jsfiddle.net/nHnrd/10/
Also, this article was helpful:
http://www.wduffy.co.uk/blog/keep-element-in-view-while-scrolling-using-jquery/

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