Update scroll position on resize of window - javascript

I'm currently using a combination of smooth scroll and IDs/anchor tags to scroll to content on my site. The code below is getting the ID of the next 'section' in the DOM, and adding it's ID as the 'view next section' href, so once it's clicked, it'll scroll to the top of that div. Then, it iterates through, updating the href with the next ID each time etc until the last section is seen and it scrolls back to the top. Pretty straightforward.
The only problem is that the 'sections' are fullscreen images, so as it's scrolling to the top of the next section, if you resize the browser, the top position of that section (where we scrolled to) has moved, and means the position is lost.
I've created a JSFiddle. You can see this happening after you click the arrow to visit the next section then resize the window: http://jsfiddle.net/WFQ9t/3/
I'm wanting to keep this top position fixed at all times so even if you resize the browser, the scroll position is updated to reflect this.
Thanks in advance,
R
var firstSectionID = $('body .each-section').eq(1).attr('id');
$('.next-section').attr('href', '#' + firstSectionID);
var i = 1;
$('.next-section').click(function() {
var nextSectionID = $('body .each-section').eq(i).attr('id');
i++;
$('.next-section').attr('href', '#' + nextSectionID);
var numberOfSections = $('body .each-section').length;
var lastSectionID = $('body .each-section').eq(numberOfSections).attr('id');
if ($('.next-section').attr('href') == '#' + lastSectionID ) {
$('.next-section').attr('href', '#introduction');
i = 1;
}
});

Ok, Please check out this fiddle: http://jsfiddle.net/WFQ9t/9/
The few things I did were:
Made some global variables to handle the screen number (which screen you're on and also the initial window height. You will use this when the screen loads and also when you click on the .next-session arrow.
var initWinHeight = $(window).height();
var numSection = 0;
Then I tossed those variables into your resizeContent() function
resizeContent(initWinHeight, numSection)
so that it will work on load and resize
I made the body move around where it needs to, to accomodate for the movement of the divs (I still don't understand what divs are moving when the regular animation happens).
$('body').css({
top: (((windowHeight - initWinHeight)*numSection)*-1) + "px"
});
Then in your click function, I add 1 to the section number, reset the initial window height and then also reset the body to top:0. The normal animation you have already puts the next section at the top of the page.
numSection++;
initWinHeight = $(window).height();
$('body').css({top:"0px"}, 1000);
Finally, I reset the numSections counter when you reach the last page (You might have to make this 0 instead of 1)
numSection = 0;
The fiddle has all of this in the correct places, these are just the steps I took to change the code.

Here is a solution that i found, but I dont use anchor links at this point, i use classes
Here is my HTML code:
<section class="section">
Section 1
</section>
<section class="section">
Section 2
</section>
<section class="section">
Section 3
</section>
<section class="section">
Section 4
</section>
And here is my jQuery/Javascript code,
I actually used a preety simple way:
$('.section').first().addClass('active');
/* handle the mousewheel event together with
DOMMouseScroll to work on cross browser */
$(document).on('mousewheel DOMMouseScroll', function (e) {
e.preventDefault();//prevent the default mousewheel scrolling
var active = $('.section.active');
//get the delta to determine the mousewheel scrol UP and DOWN
var delta = e.originalEvent.detail < 0 || e.originalEvent.wheelDelta > 0 ? 1 : -1;
//if the delta value is negative, the user is scrolling down
if (delta < 0) {
next = active.next();
//check if the next section exist and animate the anchoring
if (next.hasClass('section')) {
var timer = setTimeout(function () {
$('body, html').animate({
scrollTop: next.offset().top
}, 800);
next.addClass('active')
.siblings().removeClass('active');
clearTimeout(timer);
}, 200);
}
} else {
prev = active.prev();
if (prev.length) {
var timer = setTimeout(function () {
$('body, html').animate({
scrollTop: prev.offset().top
}, 800);
prev.addClass('active')
.siblings().removeClass('active');
clearTimeout(timer);
}, 200);
}
}
});
/*THE SIMPLE SOLUTION*/
$(window).resize(function(){
var active = $('.section.active')
$('body, html').animate({
scrollTop: active.offset().top
}, 10);
});

Related

How to keep class active when scrolling with javascript?

I need help figuring out what is going on with my javascript. I have some code that is supposed to make the nav links have an active class when you are on that part of the page, but it's only sort of working for a couple links and it also flickers as you scroll rather than staying active the whole time you're on that part of the page. See the JSFiddle for an example https://jsfiddle.net/7szpuqsr/ -- if you scroll slowly you can see how "home" becomes active for a moment. I am trying to get each link to have the active class when you click it and also while you are on that entire part of the page.
I also have a javascript sticky nav bar and smooth scrolling working so I don't know if possibly any of that is getting in the way? Thanks in advance for help.
Here's the Javascript I'm trying to use for the active class:
var sections = $('section')
, nav = $('nav')
, nav_height = nav.outerHeight();
$(window).on('scroll', function () {
var cur_pos = $(this).scrollTop();
sections.each(function() {
var top = $(this).offset().top - nav_height,
bottom = top + $(this).outerHeight();
if (cur_pos >= top && cur_pos <= bottom) {
nav.find('a').removeClass('active');
sections.removeClass('active');
$(this).addClass('active');
nav.find('a[href="#'+$(this).attr('id')+'"]').addClass('active');
}
});
});
nav.find('a').on('click', function () {
var $el = $(this)
, id = $el.attr('href');
$('html, body').animate({
scrollTop: $(id).offset().top - nav_height
}, 500);
return false;
});
Something like this? I couldn't reproduce the flickering visually on my machine but I can see the class being removed/added constantly on scroll
https://jsfiddle.net/7szpuqsr/1/
Main changes, I added a class to your sections, you have too many sections but with the way your code is meant to work, it's much easier to add a class to the sections, example below
<section id="home" class="section">
var sections = $('.section') to get the section class
updated this part of the js to check for active class
if (cur_pos >= top && cur_pos <= bottom) {
if(!$(this).hasClass("active")) {
nav.find('a').removeClass('active');
sections.removeClass('active');
$(this).addClass('active');
nav.find('a[href="#'+$(this).attr('id')+'"]').addClass('active');
}
}
You can also cache the $(this) into a variable inside of the section loop like
var $this = $(this);
then just use $this for the rest of the loop
here is the doc for hasClass https://api.jquery.com/hasclass/

Problems with scrollTop animation

I have three divs, each one with some hidden content. When you click on a div, its content is being displayed by sliding down. And at the same time, I'm using scrollTop to make the browser scroll to the top of the block thats been clicked on. The HTML looks like this:
<div class="blocks block1"></div>
<div class="content block1_content"></div>
<div class="blocks block2"></div>
<div class="content block2_content"></div>
<div class="blocks block3"></div>
<div class="content block3_content"></div>
However, im having problems with parts of the scrollTop animation. Here is the JS:
$('.blocks').on("click", function() {
if (!$(this).hasClass('expanded')) {
collapseExpandedFunction();
$('html, body').animate({
scrollTop: $(this).offset().top
}, 500);
$(this).addClass('expanded');
$(this).next().slideDown();
} else if ($(this).hasClass('expanded')) {
collapseExpandedFunction();
}
});
collapseExpandedFunction = function() {
$('.blocks.expanded').removeClass('expanded');
$('.content').slideUp();
};
I made an jsfiddle to easier demonstrate the problem: https://jsfiddle.net/ss53ckyk/3/
Explaination:
If you start toggle the green block and then toggle the red or blue, it's all good. The greens content is being hidden, while the red/blue is displayed and scrolled to the top of the block.
The problem is if you start from the top and moving down. If you first toggle the red one and then either blue or green, the browser won't scroll down correctly.
Another thing i'd like is to make the slideDown happen after the scrollTop animation is done.
Hopefully someone can help me out!
EDIT:
There should only be one blocks content visible at a time. For example, if you click the red once and then the blue, the content of the red should slide up, while the blue is showing.
The asynchronous nature of javascript is causing your issues; namely .slidUp() function. When this event is triggered, it fires an asynchronous event, which is non-blocking to the rest of the function. Therefore, the animate top will take a snapshot of the DOM at a particular moment in time while the .slidUp() function is actioning. Replacing the .slidUp() and .slidDown() with .show() and .hide() to resolve this, but this doesn't provide the responsiveness you require. One thought would be to capture the offsets of each previous content div and use that in the scrollTop function.
EDIT :
Based on the edit, you need to make few adjustments in your code which calculates the scrolltop position based on scrollposition and adding margin based on the corresponding .content div
$(document).ready(function() {
var addMargin = false;
$('.blocks').on("click", function() {
if (!$(this).hasClass('expanded')) {
collapseExpandedFunction();
var doc = document.documentElement;
var ele = this;
var nextEle = $(ele).next();
$(this).addClass('expanded');
var margin = 0;
var scrollTo = 0;
if($(ele).hasClass('expanded'))
{
if(addMargin)
margin = $(nextEle).css('height').replace('px','');
scrollTo = $(ele).offset().top - margin;
}
if(doc.scrollTop != 0 && doc.scrollTop > scrollTo && addMargin)
{
console.log(margin);
scrollTo = scrollTo + 200;
}
$('html, body').animate({
scrollTop: scrollTo
}, 500, function()
{
$(ele).next().slideDown();
});
} else if ($(this).hasClass('expanded')) {
collapseExpandedFunction();
}
});
collapseExpandedFunction = function()
{
$('.blocks.expanded').removeClass('expanded');
$('.content').slideUp();
addMargin = false;
};
window.onscroll = function (e) {
addMargin = true;
}
});
Here's the working code : https://jsfiddle.net/ss53ckyk/13/

How do I code JQuery so that when I scroll to a certain element, Nav bar appears at top, when I scroll back up past that element, nav bar disappears

I have a div called #menu which I want to display when I scroll past the element #section3, if I scroll up past that element again, I want #menu to disappear
How would I code this?
Maybe something like this?
scrolled = "no"
$(window).scroll(function(){
scr = $("body").scrollTop();
if (scr > 100 && scrolled == "no"){
$("#menu").css({"display:block"})
displayed = "yes"
}
if (displayed == "yes" && scrolled = "yes"){
$("#menu").css({"display:none"})
}
});
The above assumes that #section3 is 100 pixels down the page. If you do not know where its going to be on the page then you could use the method outlined here:
Trigger event when user scroll to specific element - with jQuery
With jQuery you can get the scroll position with $("body").scrollTop();.
Expanding on what #Ned Hulton said, I recommend comparing the scroll position to the top of a "container element" (or 'row') in your page like this:
if ($('body').scrollTop() > $('#someRow').offset().top){
//do something
}
That way you can account for your container appearing at a variable distance down the page (which will come in handy for mobile browsing or cases where your text wraps to additional lines)
I just whipped this up in jsfiddle
https://jsfiddle.net/rb56j0yu/
it uses jQuery, and checks the scroll position against the target div. Css sets the menu as position: fixed, and defaults to hidden.
$(window).scroll(function(){
var yPos = $("body").scrollTop();
var yCheck = $("#c3").position().top;
if (yPos > yCheck && !$("#menu").is(":visible"))
{
$("#menu").show();
}
if (yPos <= yCheck && $("#menu").is(":visible"))
{
$("#menu").hide();
}
});
First, get your #section3 top offset and height. Which will be used as the threshold whether #section3 is actually on the window screen.
var top = $('#section3').offset().top;
var bot = topOffset + $('#section3').height();
Then, detect it on your scroll event.
$(window).on('scroll', function () {
var scrollTop = $(window).scrollTop();
if (scrollTop >= top && scrollTop <= bot) {
// #section3 is within the screen.
$('#menu').show();
}
else {
// #section3 is out of screen.
$('#menu').hide();
}
});
This is a common use case, I wrote following code:
// what does "Auto Header" mean, goto https://www.yahoo.com/
// scroll down and you will see the purple part auto fixed to top,
// while when scroll up, it restores and does not be fixed.
// 1. multiple auto header elements handled
// 2. dynamically create/remove elements issue handled
// 3. no unnecessary dom operation, high performance
// usage: just add 'class="auto-header"' to any element you want to auto header
// suggest set each auto-header element specific width and height
// do not guarantee it works when resize or scroll left/right
$(document).ready(function() {
var rawTops = [],
rawLefts = [],
rawStyles = [],
$locations = [], // record next sibling so that element easily find where to restore
fixed = []; // mark whether this element is fixed
$(".auto-header").each(function() {
var $this = $(this),
offset = $this.offset();
rawTops.push(offset.top);
rawLefts.push(offset.left);
rawStyles.push($this.attr("style"));
$locations.push($this.siblings().eq($this.index()));
fixed.push(false);
});
$(window).on("scroll", function() {
$(".auto-header").each(function(i, e) {
if(!fixed[i] && $(window).scrollTop() > rawTops[i]) {
var $te = $(this).clone(true);
$(this).remove();
$locations[i].before($te);
$te.css({
"position": "fixed",
"top": 0,
"left": rawLefts[i],
"z-index": 100
});
fixed[i] = true;
} else if(fixed[i] && $(window).scrollTop() < rawTops[i]) {
$(this).removeAttr("style").attr("style", rawStyles[i]);
fixed[i] = false;
}
});
});
});

scroll to with easing does not work with infinite js. scroll to with easing conflicting with infinite js

PLEASE VIEW SOURCE CODE ON BOTH PAGES.
On this page: _p1.html It is "page 1" Use the scroll bar on the right side of the browser to scroll all the way down to bottom of page. "page 2" will appear. I am using infinite scroll js.
I am also using scroll to anchor point with easing. Go back to top of the page again: _p1.html Click on "scroll down to item A" It scrolls down to middle of page with easing. Now, scroll down even more. Page 2 loads. Great. Now, click on "scroll down to item B" Item B just jumps to the middle page when it supposed to scroll with easing.
What is wrong? How do I fix this?
If you go directly to page 2 here: _p2.html Click on item B. You will see that easing works. BUT when on page 1 AND infinite js, the easing scroll does not work.
What is wrong? How do I fix this?
The scroll to js is fired off at page load and is not running again when new content is loaded into the page. Therefore the scroll effect will not work on any additional content loaded into the page (page2, page3, and so on). we need to find a way to re-trigger the javascript when new content is introduced and loaded into the page.
You can attach the event handler to a parent, in this case I've used $(document) but to avoid excess overhead use the closest parent, then tell jQuery to only bubble-up the event to '.page-scroll'. This way if any new elements are added to the document which have the class page-scroll this event will be attached to them as well.
$(function() {
$(document).on('click', '.page-scroll', function(e) {
e.preventDefault();
var $anchor = $(e.target);
$('html, body').stop().animate({
scrollTop: $($anchor.attr('href')).offset().top
}, 2500, 'easeInOutExpo');
});
});
EDIT
To make this work in your situation where the script may be included more than once, you have to make sure to only load jQuery, bootstrap and jasny once, then wrap the rest of the script in a window.onload event handler. as the window only loads once, if the script is included after the window is loaded it will not be executed.
I've also reduced the included jquery easings to only include easeInOutExpo which is the easing you are using in your function.
Replace all of the scripts on each page with the following script.
<script>
if (typeof jQuery == 'undefined') {
var newJQuery = document.createElement('script');
newJQuery.type = 'text/javascript';
newJQuery.src = 'https://code.jquery.com/jquery-2.1.1.min.js';
document.body.appendChild(newJQuery);
window.jQueryInterval = window.setInterval(function(){
if(typeof jQuery != 'undefined') {
window.clearInterval(window.jQueryInterval);
var newBootstrap = document.createElement('script');
newBootstrap.type = 'text/javascript';
newBootstrap.src = 'https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/js/bootstrap.min.js';
document.body.appendChild(newBootstrap);
var newJasny = document.createElement('script');
newJasny.type = 'text/javascript';
newJasny.src = 'https://cdnjs.cloudflare.com/ajax/libs/jasny-bootstrap/3.1.3/js/jasny-bootstrap.min.js';
document.body.appendChild(newJasny);
/******************************************
Infinite jQuery Scroll
#author Fabio Mangolini
http://www.responsivewebmobile.com
******************************************/
//location.href = 'index.html#start';
var pages = []; //key value array that maps the pages. Ex. 1=>page2.html, 2=>page3.html
var current = 0; //the index of the starting page. 0 for index.html in this case
var loaded = []; //key value array to prevent loading a page more than once
//get all the pages link inside the #pages div and fill an array
$('#pages a').each(function(index) {
pages[index] = $(this).attr('href');
loaded[$(this).attr('href')] = 0; //initialize all the pages to be loaded to 0. It means that they are not yet been loaded.
});
//on scroll gets when bottom of the page is reached and calls the function do load more content
$(window).scroll(function() {
//Not always the pos == h statement is verified, expecially on mobile devices, that's why a 300px of margin are assumed.
if ($(window).scrollTop() + $(window).height() >= $(document).height() - 300) {
console.log("bottom of the page reached!");
//in some broswer (es. chrome) if the scroll is fast, the bottom
//reach events fires several times, this may cause the page loaging
//more than once. To prevent such situation every time the bottom is
//reached the number of time is added to that page in suach a way to call
//the loadMoreContent page only when the page value in "loaded" array is
//minor or equal to one
loaded[pages[current + 1]] = loaded[pages[current + 1]] + 1;
if (loaded[pages[current + 1]] <= 1)
loadMoreContent(current + 1);
}
});
//loads the next page and append it to the content with a fadeIn effect.
//Before loading the content it shows and hides the loaden Overlay DIV
function loadMoreContent(position) {
//try to load more content only if the counter is minor than the number of total pages
if (position < pages.length) {
$('#loader').fadeIn('slow', function() {
$.get(pages[position], function(data) {
$('#loader').fadeOut('slow', function() {
$('#scroll-container').append(data).fadeIn(999);
current = position;
});
});
});
}
}
jQuery.extend(jQuery.easing, {
easeInOutExpo: function(e, f, a, h, g) {
if (f === 0) {
return a;
}
if (f === g) {
return a + h;
}
if ((f /= g / 2) < 1) {
return h / 2 * Math.pow(2, 10 * (f - 1)) + a;
}
return h / 2 * (-Math.pow(2, -10 * --f) + 2) + a;
}
});
/*jQuery to collapse the navbar on scroll
$(window).scroll(function() {
if ($(".navbar").offset().top > 50) {
$(".navbar-fixed-top").addClass("top-nav-collapse");
} else {
$(".navbar-fixed-top").removeClass("top-nav-collapse");
}
});
*/
//jQuery for page scrolling feature - requires jQuery Easing plugin
$(document).on('click', '.page-scroll', function(e) {
var $anchor = $(this);
$('html, body').stop().animate({
scrollTop: $($anchor.attr('href')).offset().top
}, 2500, 'easeInOutExpo');
e.preventDefault();
});
}
},1);
};
</script>

How can I set my browser window's scrollbar or a div scrollbar to scroll in increments using animate and scrollTop?

The general idea to the site i am designing is to scroll through a set of menu items horizontally and incrementally underneath a static div that will magnify(increase dimensions and pt size) the contents of a menu items. I don't really need help with the magnify portion because i think it's as simple as adding a mag class to any of the menuItem divs that go underneath the static div. I have been messing with this for a few weeks and the code I have for incrementally scrolling, so far, is this:
$(document).ready(function () {
currentScrollPos = $('#scrollableDiv').scrollTop(120); //sets default scroll pos
/*The incrementScroll function is passed arguments currentScrollPos and UserScroll which are variables that i have initiated earlier in the program, and then initiates a for loop.
-The first statement sets up the variables: nextScrollPos as equal to the currentScrollPos(which by default is 120px) plus 240px(the distance to next menuItem), prevScrollPos as equal to the currentScrollPos(which by default is 120px) minus 240px(the distance to next menuItem).
-The second Statement checks to see if the user has scrolled using var userScroll
-The third statement sets: var CurrentScroll equal to the new scroll position and var userScroll to false*/
function incrementScroll(currentScrollPos, userScroll) {
for (var nextScrollPos = parseInt(currentScrollPos + 240, 10),
prevScrollPos = parseInt(currentScrollPos - 240, 10); //end first statement
userScroll == 'true'; console.log('dude'), //end second statement and begining of third
currentScrollPos = scrollTop(), userScroll = 'false') {
if (scrollTop() < currentScrollPos) {
$('#scrollableDiv').animate({
scrollTop: (parseInt(prevScrollPos, 10))
}, 200);
console.log('scrolln up')
} else if (scrollTop() > currentScrollPos) {
$('#scrollableDiv').animate({
scrollTop: (parseInt(nextScrollPos, 10))
}, 200);
console.log('scrolln down')//fire when
}
}
}
$('#scrollableDiv').scroll(function () {
userScroll = 'true';
_.debounce(incrementScroll, 200); //controls the amount of times the incrementScroll function is called
console.log('straight scrolln')
});
});
I have found a variety of solutions that are nigh close: such as a plugin that snaps to the next or previous div horizontally demo, another solution that also snaps and is based on setTimeout demo, but nothing that nails incrementally scrolling through divs. I also found a way to control the rate at which a user may scroll through the menuItems using debounce which is included in the above code.
The console.logs inside the loop do not fire when I demo the code in jsfiddle which leads me to believe the problem lies within the loop. I'm a noob though so it could be in syntax or anywhere else in the code for that matter. Also in the second demo, i have provided the css for the horizontal static div, but the moment I put it in my html it keeps the js from working.
I would like to write the code instead of using a plugin and any help would be appreciated! Also, thank you ahead of time!
Try this fiddle. Menu container height is 960px to show 4 menu items. "Zoom" div is positioned absolutely at top. When you scroll mouse over this div, menu items shifts to top/bottom. I had to add additional div to bottom to be able to scroll to last 3 menu items. JS code:
jQuery(document).ready(function($){
var current = 0;
var menu = $('.menu-container').scrollTop(0);
var items = menu.find('.menu-item');
var zoom = $('.zoom');
function isVerticalScroll(event){
var e = event.originalEvent;
if (e.axis && e.axis === e.HORIZONTAL_AXIS)
return false;
if (e.wheelDeltaX)
return false;
return true;
}
function handleMouseScroll(event){
if(isVerticalScroll(event)){
var delta = event.originalEvent.wheelDelta * -1 || event.originalEvent.detail;
current += (delta > 0 ? 1 : -1);
if(current < 0)
current = 0;
if(current >= items.length){
current = items.length - 1;
}
menu.stop().animate({
"scrollTop": current * 240
}, 300);
items.removeClass('current').eq(current).addClass('current');
event && event.preventDefault();
return false;
}
}
zoom.on({
"MozMousePixelScroll": handleMouseScroll,
"mousewheel": handleMouseScroll
});
});
Hope it will help.

Categories