How to execute a function when the scroll reaches an element? - javascript

I want to hide all elements but the first one so I use $(".item:not(:eq(0))").fadeOut();
I have elements with the same class "item":
<div class="item">First Item</div>
<div class="item">Second Item</div>
<div class="item">Third Item</div>
<div class="item">Fourth Item</div>
Then when I scroll to the next element which could be "second , third,fourth item" , I want to show it
I tried using :
function isScrolledIntoView(elem)
{
var centerY = Math.max(0,((jQuery(window).height()-
jQuery(elem).outerHeight()) / 2)
+ jQuery(window).scrollTop());
var elementTop = jQuery(elem).offset().top;
var elementBottom = elementTop + jQuery(elem).height();
return elementTop <= centerY && elementBottom >= centerY;
}
jQuery(window).on("scroll resize", function() {
jQuery(".news:not(:eq(0))").each(function(index, element) {
if (isScrolledIntoView(element)) {
jQuery(element).fadeIn(10000);
}
});
});
But it doesn't work with my method because the height of the body changes on showing the next item "Second Item" , So All the items are shown when I scroll to the "Second Item" or any other item.
How to hide the items but the first one and then fadIn() each on scrolling to it ?

This is using offset() in jquery. This demo will trigger function if
your element is completely in your viewport.
Tip:You need to take care of inner as well as outer height of element.
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<style>
body{
height:200vh;
}
#test {
top: 100vh;
padding: 10px;
width: 300px;
position: relative;
border: 1px solid black;
height:100;
}
</style>
</head>
<body>
<p>scroll to test</p>
<div id="test">
<p>Click the button to get offsetTop for the test div.</p>
</div>
<script>
$(document).ready(function(){
$(window).scroll(function(){
var x = $("#test").offset();
var height1 = $("#test").outerHeight();
var y = document.documentElement.scrollTop;
var z = (x.top + height1) - y;
if(z < $(window).height()){
alert("fumction");
}
});
});
</script>
</body>
</html>

It will be more easy to use the combination of waypoint.js and animate.css.
Add animated class to every element to be animated. You can use any of the animate.css effects.
Change the offset { offset: '80%' } to control when the animation can start.
<div class="animated waypoint-slideup">
</div>
$('.waypoint-slideup').waypoint(function () {
$(this).addClass('slideInUp');
}, { offset: '80%' });
Use this in the css file
.waypoint-slideup{
opacity:0;}
.waypoint-slideup.slideInUp{
opacity:1;}

Related

How to detect correct div data attribute when each hitting the top of the page

I am working on the below code. Why am I not able to detect which div is reaching at the top of page in both down or up scroll?
$(window).scroll(function() {
$(".container").each(function() {
var $that = $(this);
var po = $(this).offset().top;
if (po >= 0 && po <= 300) {
console.log($that.data('map'));
}
});
});
.container {
height: 690px;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="container" data-map="One">One</div>
<div class="container" data-map="Two">Tow</div>
<div class="container" data-map="Three">Three</div>
<div class="container" data-map="Four">Four</div>
<div class="container" data-map="Five">Five</div>
You'll need to use $(window).scrollTop(); as well as $that.outerHeight()
$(window).scroll(function() {
var windowScrollTop = $(this).scrollTop(); // window scroll top
$(".container").each(function() {
var $that = $(this);
var po = $that.offset().top;
var poHeight = $that.outerHeight(true); // the height of the element
var distanceTop = 100; // the distance from top to run the action .. it can be 0 if you want to run the action when the element hit the 0 top
if (windowScrollTop + distanceTop >= po && windowScrollTop + distanceTop <= po + poHeight) {
if(!$that.hasClass('red')){ // if element dosen't has class red
console.log($that.data('map'));
$(".container").not($that).removeClass('red'); // remove red class from all
$that.addClass('red'); // add red class to $that
}
}
});
}).scroll(); // run the scroll onload
.container {
height: 690px;
}
.container.red{
background : red;
color : #fff;
font-size: 30px;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="container" data-map="One">One</div>
<div class="container" data-map="Two">Two</div>
<div class="container" data-map="Three">Three</div>
<div class="container" data-map="Four">Four</div>
<div class="container" data-map="Five">Five</div>

Change active state on scroll to viewport

I'm trying to make a single static website, which when an div child of comes into viewport (precisely, when div element comes into the upper 50% of the viewport) changes the corresponding div's class in side-nav to "active". It should work scrolling down and up.
So far I've tried several solution from other threads on SO, none successful. I assume I've been approaching this wrong.
$(window).on('scroll', function() {
$("#vars-args").each(function() {
if (elementInViewport2($(this))) {
$(this).find("#div1a").addClass("active");
}
});
});
function elementInViewport2(el) {
var top = el.offsetTop;
var left = el.offsetLeft;
var width = el.offsetWidth;
var height = el.offsetHeight;
while (el.offsetParent) {
el = el.offsetParent;
top += el.offsetTop;
left += el.offsetLeft;
}
return (
top < (window.pageYOffset + window.innerHeight) &&
left < (window.pageXOffset + window.innerWidth) &&
(top + height) > window.pageYOffset &&
(left + width) > window.pageXOffset
);
}
<script src="https://code.jquery.com/jquery-3.3.1.js" integrity="sha256-2Kok7MbOyxpgUVvAk/HJ2jigOSYS2auK4Pfzbm7uH60=" crossorigin="anonymous"></script>
<div id="side-nav">
1
2
3
4
5
6
</div>
<div id="content">
<div id="div1">
<!--content-->
</div>
<div id="div2">
<!--content-->
</div>
<div id="div3">
<!--content-->
</div>
<div id="div4">
<!--content-->
</div>
<div id="div5">
<!--content-->
</div>
<div id="div6">
<!--content-->
</div>
</div>
Also note that content of each div inside can be larger than the size of viewport.
I have been having problems getting the javascript to work. Also please note that the current JS is copied from some other thread.
This can be achieved using the IntersectionObserver as told by #cloned in the comments: https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
To achieve this, you need a callback function passed as a parameter which is executed once isIntersecting is true, an option object (below it sets the threshold at 50% of the element) and an IntersectionObserver.
The callback toggles the active class to the a element according to the entry's id.
At the end we loop through the divs and make our observer observe them.
const callback = (entries, observer) => {
entries.forEach(entry => {
const navItem = document.querySelector('#' + entry.target.id + 'a');
if (entry.isIntersecting) {
console.log(navItem.getAttribute('id'));
navItem.classList.add('active');
} else {
navItem.classList.remove('active');
}
});
};
const options = {
threshold: 0.5
};
const observer = new IntersectionObserver(callback, options);
const container = document.getElementById('content');
const targetElements = container.querySelectorAll('div');
targetElements.forEach(element => {
observer.observe(element);
});
Here is a JSBin to demonstrate it https://jsbin.com/riyuhediso/47/edit?html,js,console,output
Note that although it demonstrates its feasibility it's not been profiled for performance issues which can be significant so I don't vouch for it.
If you are using Bootstrap you can use the ScrollSpy lib https://getbootstrap.com/docs/4.1/components/scrollspy/ and there is also ScrollMagic which is great http://scrollmagic.io/
You need to filter out which element is inside the viewport with the help of .getBoundingClientRect()
Checkout this
and check if any content has it's top and bottom within the half of the viewport ( window.innerHeight )
I took help of filter function to find out the index of contents that is within the built in function and set the .active class of the corresponding anchor.
Have a look at the snippet:
var direction = 0; // a variable to keep track of scrolled position;
$(window).on('scroll', function() {
// check if window is scrolling up or down;
if ($(window).scrollTop() > direction) { // if true, window scrolling scrolling down;
$('#side-nav').find('a').removeClass('active'); // remove active class from all anchors
$('#side-nav').find('a').eq(
// .eq() selector helps to find elements with index number, and here we pass a filter to find the content that is within the viewport;
$('#content').find('div').filter(function(index) {
return this.getBoundingClientRect().y <= (window.innerHeight / 2) && this.getBoundingClientRect().y + this.getBoundingClientRect().height > window.innerHeight / 2;
}).index()
).addClass('active');
// update the current scroll position now;
direction = $(window).scrollTop();
} else { // if false, window scrolling scrolling up;
$('#side-nav').find('a').removeClass('active'); // remove active class from all anchors
$('#side-nav').find('a').eq(
$('#content').find('div').filter(function(index) {
return this.getBoundingClientRect().y < (window.innerHeight / 2) && this.getBoundingClientRect().y + this.getBoundingClientRect().height > window.innerHeight / 2;
}).index()
).addClass('active');
// update the current scroll position now;
direction = $(window).scrollTop();
}
});
* {
margin: 0;
padding: 0;
}
#side-nav {
/* feel free to remove or change, only for testing */
position: fixed;
width: 100%;
top: 0;
padding: 15px;
}
#side-nav a {
/* feel free to remove, only for testing */
text-decoration: none;
color: grey;
margin-right: 5px;
font-size: 24px;
font-weight: bold;
}
#side-nav a.active {
color: #000;
/* sets color for the default active class */
}
#content div {
min-height: 600px;
background-color: #cecece;
border-bottom: 1px solid #fff;
box-sizing: border-box;
padding: 50px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="side-nav">
<a href="" id="div1a" class='active'>1</a>
<!-- set a default class assuming the first one will be in viewport while window loads -->
2
3
4
5
6
</div>
<div id="content">
<div id="div1">
<p>One</p>
</div>
<div id="div2">
<p>Two</p>
</div>
<div id="div3">
<p>Three</p>
</div>
<div id="div4">
<p>Four</p>
</div>
<div id="div5">
<p>Five</p>
</div>
<div id="div6">
<p>Six</p>
</div>
</div>

jQuery - element crossing another element

I have a fixed div on the page which contains a logo and as the user scrolls and this logo passes over other divs I wnat to the change the colour of the logo.
I have this working over a single div but need to it work across multiple so any help appreciated.
The WIP site can be seen here... dd.mintfresh.co.uk - if you scroll down you'll (hopefully) see the logo change from black to white as it crosses an illustrated egg. I need the same to happen when it crosses other divs further down the page.
The script so far...
jQuery(window).scroll(function(){
var fixed = jQuery("logo");
var fixed_position = jQuery("#logo").offset().top;
var fixed_height = jQuery("#logo").height();
var toCross_position = jQuery("#egg").offset().top;
var toCross_height = jQuery("#egg").height();
if (fixed_position + fixed_height < toCross_position) {
jQuery("#logo img").css({filter : "invert(100%)"});
} else if (fixed_position > toCross_position + toCross_height) {
jQuery("#logo img").css({filter : "invert(100%)"});
} else {
jQuery("#logo img").css({filter : "invert(0%)"});
}
}
);
Any help appreciated. Thanks!
you need to fire a div scroll event. you can assign
$("div1").scroll(function(){
//change the color of the div1
}
});
$("div2").scroll(function(){
//change the color of the div2
}
});
or you can assign a class to divs which you want to change the color
$(".div").scroll(function(){
//change the color of the div which you are scrolling now
}
});
You can use like this :-
$(window).scroll(function() {
var that = $(this);
$('.section').each(function() {
var s = $(this);
if (that.scrollTop() >= s.position().top) {
if(s.hasClass('active')) {
$('.logo').addClass('invert');
} else {
$('.logo').removeClass('invert');
}
}
});
});
body {
padding: 0;
margin: 0;
}
div {
background: #f00;
height: 400px;
}
.logo {
position: fixed;
top: 0;
left: 0;
width: 100px;
}
.logo.invert {
filter: invert(100%);
}
div:nth-child(even) {
background: #ff0;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<img src="https://dd.mintfresh.co.uk/wp-content/uploads/2018/06/DD_logo.svg" class="logo" />
<div id="page1" class="section"></div>
<div id="page2" class="section active"></div>
<div id="page3" class="section"></div>
<div id="page4" class="section active"></div>
<div id="page5" class="section"></div>
As your site code you can do like this :
$(window).scroll(function() {
var that = $(this);
$('#content > section').each(function() {
var s = $(this);
if (that.scrollTop() >= s.position().top) {
if(s.hasClass('black')) {
$('#logo img').css({filter: 'invert(0%)'});
} else {
$('#logo img').css({filter: 'invert(100%)'});
}
}
});
});

Fire AJAX jQuery if scroll reach to each div

I want make ajax fire if scroll reach to each div element.
Item div 1
Item div 2 (fire ajax if scroll to this element)
Item div 3 (fire ajax again if scroll to this element)
Item .....N
I use this code, but only fire if scroll to end.
$( window ).scroll( function() {
if( $( window ).scrollTop() == $( document ).height() - $( window ).height() ) {
alert('Fire!');
}
});
Please help.
Use $.offset().top instead of heights.
To check all sections you can use $.each(). Since I am guessing you only want to fire the event once, you will need a variable to remember all sections, that already fired.
let firedEvents = [];
$(window).scroll(function() {
$("div.section").each(function() {
if (!firedEvents.includes(this) && $(window).scrollTop() > $(this).offset().top) {
firedEvents.push(this);
alert("fire " + $(this).data("nr"));
}
});
});
div {
height: 500px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="section" data-nr="0" style="background-color: red;"></div>
<div class="section" data-nr="1" style="background-color: green;"></div>
<div class="section" data-nr="2" style="background-color: blue;"></div>
<div class="section" data-nr="3" style="background-color: yellow;"></div>
I took the liberty of writing a simple html that will fullfil your needs.
In my example scroll happens via button click; u can change it with your usecase; Hope this helps; here's the fiddle https://jsfiddle.net/39z82axt/
html
<div id="wrapper">
<div class="divel">Element 1</div>
<div class="divel">Element 2</div>
<div class="divel">Element 3</div>
<div class="divel">Element 4</div>
<div class="divel">Element 5</div>
</div>
<button id="scrollButton">
Click to Scroll
</button>
css
.divel {
height:80px;
}
#wrapper {
height: 100px;
overflow:scroll;
}
js
let crossedFirstDiv = false,
crossedSecondDiv = false;
document.getElementById('scrollButton').onclick = function() {
document.getElementById("wrapper").scrollTop += 10;
let scrollLocation = scrollPosition("wrapper");
if (scrollLocation > 10 && scrollLocation <20 && crossedFirstDiv == false) {
alert("crossing div 1");
crossedFirstDiv = true;
}
else if (scrollLocation > 20 && scrollLocation <30 && crossedSecondDiv == false) {
crossedSecondDiv = true;
alert("crossing div 2");
}
// and so on..
}
function scrollPosition(elementId) {
let a = document.getElementById(elementId).scrollTop;
let b = document.getElementById(elementId).scrollHeight - document.getElementById(elementId).clientHeight;
let c = a / b;
return Math.floor(c * 100);
}
$(window).scroll( function() {
var scrolled = $( window ).scrollTop();
$('div:not(.fired)').each(function () {
var position_of_div = $(this).offset();
if (scrolled > position_of_div.top) {
$(this).addClass('fired');
alert('fire');
}
});
});
Save the scrolled pixels in an variable. On scroll get the position of each div. If the amount of pixels scrolled is greater than the offset of the div (related to the document) fire a AJAX call.

How can I change the x position of a div via javascript when I click on another div this way?

<body>
<div id = "SiteContainer">
<div id = "NavigationButtons"></div>
<div id = "ShowReelContainer">
<div id= "NavigationBackward" name = "back" onclick="setPosition();">x</div>
<div id= "NavigationForward" name = "forward" onclick="setPosition();">y</div>
<div id = "VideoWrapper">
<div id = "SlideShowItem">
<img src="Images/A.png" alt="A"></img>
</div>
<div id = "SlideShowItem">
<img src="Images/B.png" alt="B"></img>
</div>
<div id = "SlideShowItem">
<img src="Images/C.png" alt="C" ></img>
</div>
</div>
</div>
</div>
<script>
var wrapper = document.querySelector("#VideoWrapper");
function setPosition(e)
{
if(e.target.name = "forward")
{
if!(wrapper.style.left = "-200%")
{
wrapper.style.left = wrapper.style.left - 100%;
}
}
else
{
if(e.target.name = "back")
{
if!(wrapper.style.left = "0%")
{
wrapper.style.left = wrapper.style.left + 100%;
}
}
}
}
</script>
</body>
Hi, I am very new to javascript. What I am trying to do, is change the x-position of a div when another div (NavigationForward or NavigationBackward) is clicked. However it does not appear to do anything at all. Basically if the div with name forward is clicked, I want to translate the VideoWrapper -100% from it's current position and +100% when "back". The css div itself VideoWrapper has a width of 300%. Inside this div as you can see is a SlideShowItem which is what will change. Perhaps I am adding and subtracting 100% the wrong way?
EDIT:
Thanks everyone for helping me out with this...I had just one more query, I am trying to hide the arrows based on whether the wrapper is at the first slide or the last slide. If its on the first slide, then I'd hide the left arrow div and if it's on the last, I'd hide the right arrow, otherwise display both of em. Ive tried several ways to achieve this, but none of em work, so Ive resorted to using copies of variables from the function that works. Even then it does not work. It appears that my if and else if statements always evaluate to false, so perhaps I am not retrieving the position properly?
function HideArrows()
{
var wrapper2 = document.getElementById("VideoWrapper");
var offset_x2 = wrapper2.style.left;
if(parseInt(offset_x2,10) == max_x)
{
document.getElementById("NavigationForward").display = 'none';
}
else if(parseInt(offset_x2,10) == min_x)
{
document.getElementById("NavigationBackward").display = 'none';
}
else
{
document.getElementById("NavigationForward").display = 'inline-block';
document.getElementById("NavigationBackward").display = 'inline-block';
}
}
//html is the same except that I added a mouseover = "HideArrows();"
<div id = "ShowReelContainer" onmouseover="HideArrows();">
To achieve this type o slider functionality your div VideoWrapper must have overflow:hidden style, and your SlideShowItemdivs must have a position:relative style.
Then to move the slides forward or backward you can use the style left which allows you to move the divs SlideShowItem relative to it's parent VideoWrapper.
I've tested this here on JSFiddle.
It seems to work as you described in your question, although you may need to do some adjustments, like defining the width of your slides, how many they are and so on.
For the sake of simplicity, I defined them as "constants" on the top of the code, but I think you can work from that point on.
CSS
#VideoWrapper{
position:relative; height:100px; white-space:nowrap;width:500px;
margin-left:0px; border:1px solid #000; overflow:hidden; }
.SlideShowItem{
width:500px; height:100px;display:inline-block;position:relative; }
#NavigationForward, #NavigationBackward{
cursor:pointer;float:left; background-color:silver;margin-right:5px;
margin-bottom:10px; text-align:center; padding:10px; }
HTML
<div id = "SiteContainer">
<div id = "NavigationButtons">
</div>
<div id = "ShowReelContainer">
<div id= "NavigationBackward" name = "back" onclick="setPosition('back');">prev</div>
<div id= "NavigationForward" name = "forward" onclick="setPosition('forward');">next</div>
<div style="clear:both;"></div>
<div id = "VideoWrapper">
<div class= "SlideShowItem" style="background-color:blue;">
Slide 1
</div>
<div class = "SlideShowItem" style="background-color:yellow;">
Slide 2
</div>
<div class = "SlideShowItem" style="background-color:pink;">
Slide 3
</div>
</div>
</div>
</div>
JavaScript
var unit = 'px'; var margin = 4; var itemSize = 500 + margin; var itemCount = 3; var min_x = 0; var max_x = -(itemCount-1) * itemSize;
function setPosition(e) {
var wrapper = document.getElementById("VideoWrapper");
var slides = wrapper.getElementsByTagName('div');
var offset_x = slides[0].style.left.replace(unit, '');
var curr_x = parseInt(offset_x.length == 0 ? 0 : offset_x);
if(e == "forward")
{
if(curr_x <= max_x)
return;
for(var i=0; i<slides.length; i++)
slides[i].style.left= (curr_x + -itemSize) + unit;
}
else if(e == "back")
{
if(curr_x >= min_x)
return;
for(var i=0; i<slides.length; i++)
slides[i].style.left= (curr_x + itemSize) + unit;
} }
After you analyze and test the code, I don't really know what's your purpose with this, I mean, you maybe just playing around or trying to develop something for a personal project, but if you are looking for something more professional avoid to create things like sliders on your own, as there are tons of plugins like this available and well tested out there on the web.
Consider using jQuery with NivoSlider, it works like a charm and is cross browser.
I would recommend using jQuery, this will reduce your coding by quite a bit. Can read more here: http://api.jquery.com/animate/
I've created a simple fiddle for you to take a look at. This example uses the .animate() method to reposition two div elements based on the CSS 'left' property.
CSS:
#container {
position: absolute;
left: 1em;
top: 1em;
right: 1em;
bottom: 1em;
overflow: hidden;
}
#one, #two {
position: absolute;
color: white;
}
#one {
background: pink;
width: 100%;
top:0;
bottom:0;
}
#two {
background: blue;
width: 100%;
left: 100%;
top:0;
bottom:0;
}
HTML:
<div id="container">
<div id="one">Div One</div>
<div id="two">Div Two</div>
</div>
JavaScript/jQuery:
var one, two, container;
function animateSlides(){
one.animate({
left : '-100%'
}, 1000, function(){
one.animate({
left : 0
}, 1000);
});
two.animate({
left : 0
}, 1000, function(){
two.animate({
left:'100%'
}, 1000);
});
};
$(function(){
one = $('#one');
two = $('#two');
container = $('#container');
setInterval(animateSlides, 2000);
});
JSFiddle Example: http://jsfiddle.net/adamfullen/vSSK8/3/

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