Develop Reference

Temporarily Stop One Function Execution with setTimeOut() when a Button is Clicked

I have an animation triggered by a scroll event, which makes a menu slide out of view. There is also a button that when clicked brings the menu back into view.
Because the menu can be closed by scrolling, when the user clicks the button to bring the menu in, if they scroll during this period of the animation, the menu disappears again without the animation completing.
I have put together a simplified version of the animation here http://codepen.io/emilychews/pen/evbzMQ
I need to temporarily prevent the scroll function working after the button is clicked, which I'm assuming would be best done with the setTimeout() method on the click function? I've tried a number of things but can't seem to solve it/ get it to work.
Any help would be awesome. For quick reference as well the code is below
JQUERY
jQuery(document).ready(function($){
// slide menu to left on scroll
function hideOnScroll() {
$(window).scroll(function() {
if ( $(document).scrollTop() > 1) {
$('.menubox').css('left', '-25%');
}
});
}
hideOnScroll(); // call hideOnScroll function
// click handler to bring menu back in
$('.mybutton').on('click', function() {
$('.menubox').css('left', '0%');
var scrollPause = setTimeout(hideOnScroll, 2000) // temporarily pause hideOnScroll function
});
}); //end of jQuery
CSS
body {
margin: 0;
padding: 0;
height: 200vh;}
.menubox {
top: 100;
position: fixed;
width: 20%;
height: 100%;
background: red;
padding: 10px;
color: white;
transition: all 2s;
}
.mybutton {
position: fixed;
left: 40%;
top: 50px;
padding: 5px 10px;
}
HTML
<div class="menubox">Menu Box</div>
<button class="mybutton">Click to bring back menu</button>
** Also please note I've simplified the animation for the sake of the forum, the actual animation function contains Greensock code, but I didn't want to include this in case it confused the issue. I can't therefore just use the .addClass() and .removeClass() or have a workaround that changes the given CSS or scrollTop() values. I need to disable the hideOnScroll() function when the button is clicked for the duration of the click invoked animation - which in the examples is 2s. Thus I think the only way to achieve this is with the setTimeOut() method (i may be wrong on this). But I can't get it to work.
Many thanks
Emily

you can simply check the offset is complete.
function hideOnScroll() {
$(window).scroll(function() {
if ( $(document).scrollTop() > 1) {
if( $('.menubox').offset().left == 0 ){
$('.menubox').css('left', '-25%');
}
});
}
http://codepen.io/anon/pen/aJXGbr

I have made a few changes in your javascript. Have a look
var animating = false;
$(document).ready(function(){
function hideOnScroll() {
$(window).scroll(function() {
event.preventDefault();
if ( $(document).scrollTop() > 1 && !animating){
console.log("Hiding")
animating = true;
$('.menubox').animate({'left': '-25%'},2000,function(){
animating = false;
});
}
});
}
hideOnScroll();
$('.mybutton').click(function() {
var pos = $(window).scrollTop();
animating = true;
$('.menubox').animate({'left':'0%'},2000,function(){
console.log("Finished Opening");
animating = false;
});
console.log("Animating Open");
var siId = setInterval(function(){
if(animating){
console.log("Preventing Window Scrolling.");
$(window).scrollTop(pos);
}
else{
console.log("Stopping setInterval");
animating = false;
clearInterval(siId);
}
},0);
});
});
This will stop your browser window from scrolling until your Menu Open Animation is finished.
Also I have removed the transitionproperty from style.
Tested in Google Chrome.
Kindly inform me if i have misinterpreted your question.

Display some element user scrolling

I would like to display some element (div for example) when the user scrolling.
I seeing that a scrollTop, but isn't work. Because for sure I use badly.
I can't find some help without JQuery. I don't want to use JQuery.
I try this :
var scroll = document.body.scrollTop;
var divLis = document.querySelectorAll("div");
for(let i = 0; i < divLis.length; i++) {
if(scroll === divLis[i]) {
divLis[i].style.transform = "translateX(0)";
divLis[i].style.transition = "2s";
}
}

I honestly can't really tell what you're trying to do, but given your response to #uom-pgregorio's answer, I'm guessing you might just want a pure JS scroll listener:
window.addEventListener('scroll', function() {});

Edit: Sorry I just noticed that you didn't want jQuery but I'll just leave this here in case you change your mind.
$(window).scroll(function() {
// show the div(s)
});
That's an event handler where the function runs or fires up whenever the window or viewport scrolls.

Ok... I understand.
I wanted to try this :
* {
margin: 0;
padding: 0;
border: 0;
}
body {
height: 200vh;
}
.left {
width: 300px;
height: 300px;
background-color: red;
position: absolute;
top: 150%;
transform: translateX(-300px);
transition: 5s;
}
// HTML :
<div class="left"></div>
// JS
var divLis = document.querySelector(".left");
window.addEventListener("scroll", function (e) {
if(window.pageYOffset > 500) {
console.log(window.pageYOffset)
divLis.style.transform = "translateX(0)";
}
})
So, it's very simple and I took my head for nothing.
So thanks so much for answering me !
Enjoy your Weekend

jQuery doesn't show and hide the header

I'm trying to make a header that appears at a certain place of the page.
So what I'm doing is checking the scroll to top of the page and the top offset of the element after which the header should appear. If the scrollTop is greater than offset the header is shown, otherwise it disappears.
But! When I scroll to the place, the header position is constantly switching between top: -13% and top: -12.999998%. After some time it finally shows the header but it never disappears.
What am I doing wrong?!
JSFiddle: https://jsfiddle.net/5k5s016f/

Well, i think the problem is that the .animate() functions are running constantly, causing the animations to "restart" before its ends.
It is not the most beautiful solution, but just adding a flag that controls the execution of the functions and a timeout to run the handler less frequently solves the problem.
https://jsfiddle.net/5k5s016f/2/
var visible = false;
$(window).scroll(function() {
setTimeout(function(){
var height = $(window).scrollTop();
var $page2 = $("#page2");
var offset = $page2.offset().top;
if (height > offset) {
if (visible) {
return;
}
visible = true;
$(".floating-header").show().animate({
top: 0
});
} else {
if (!visible) {
return;
}
visible = false;
$(".floating-header").animate({
top: "-13%"
});
}
}, 200)
});

The issue you are seeing is because each time a scroll event gets called animation queues up. If you wait long enough, you can see that the animation to set top to 0 actually works.
You can use the stop() function to stop all animation before attempting to run another one.
Something like this
if (height > offset) {
$(".floating-header").stop().show().animate({
top: "0"
}, 700);
} else {
$(".floating-header").stop().animate({
top: "-13%"
}, 700);
}
A couple of improvements I can suggest are
Debounce the scroll event handler
Check the current state of the header before queuing animation. i.e. do not try to hide it if it is already hidden and vice versa

Your logic is all messed up. Basically, you want to make sure that you are only animating when you absolutely need to - no more, no less. And since scroll events happen hundreds of times... constantly rapid firing as the user scrolls... you want to make sure you are doing the least amount of work possible during each scroll event. This especially means that you don't want to be querying the DOM on every scroll event if you don't have to (ps. $('selector') is a dom query). Take a look at this fiddle:
https://jsfiddle.net/5k5s016f/6/

Looks like I'm last to the party due to interruptions, but since I wrote it up I'll post the answer FWIW.
jsFiddle Demo
You need to debounce your code. Here is a simple system, but studing Ben Alman's explanation/examples is also recommended.
var $m1 = $('#m1'), $m2 = $('#m2'); //TESTING ONLY
var $win = $(window), $page2 = $("#page2"), $hdr=$(".floating-header");
var $offset = $page2.offset().top;
var hvis = false, curpos;
$win.scroll(function() {
curpos = $win.scrollTop();
$m1.html(curpos); //TESTING ONLY
$m2.html($offset);//TESTING ONLY
if ( curpos > $offset ) {
if ( !hvis ){
hvis = true;
//$m1.html(curpos);
$hdr.finish().animate({
top: "0"
}, 700);
}
} else {
if ( hvis ){
$hdr.finish().animate({
top: "-60px"
}, 700);
hvis = false;
}
}
});
html,
body {
height: 100vh;
width: 100vw;
}
#page1,
#page2,
#page3 {
height: 100%;
width: 100%;
background-color: #fff;
}
.floating-header {
position: fixed;
top: -60px;
background-color: #000;
width: 100%;
height: 60px;
}
.msg{position:fixed;bottom:10px;height:30px;width:80px;text-align:center;}
.msg{padding-top:10px;}
#m1 {left:3px; border:1px solid orange;background:wheat;}
#m2 {right:3px;border:1px solid green; background:palegreen;}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<header class="floating-header">Header</header>
<div id="page1">
<p>Page1</p>
</div>
<div id="page2">
<p>Page2</p>
</div>
<div id="page3">
<p>Page3</p>
</div>
<div id="m1" class="msg"></div>
<div id="m2" class="msg"></div>

Javascript button appear animation

I have the back to top button that appears when you reach a point on the page, which is working fine, however, when it appears the text is on two lines until the box has finished the animation to appear. So, is there anyway to prevent this? What I mean by the animation is: btt.show('slow');
Code:
$(document).ready(function () {
var btt = $('.back-to-top');
btt.on('click' , function(e) {
$('html, body').animate({
scrollTop: 0
}, 500);
btt.hide('slow');
e.preventDefault();
});
$(window).on('scroll', function () {
var self = $(this),
height = self.height(),
top = self.scrollTop();
if (top > 500) {
btt.show('slow');
} else {
btt.hide('slow');
}
});
});
Example: http://codepen.io/Riggster/pen/WvNvQm

The problem is caused by animating the width of a box, I think it might be better to animate the position of it instead, but - even better - lets use CSS animations!
$(window).on('scroll', function () {
if ($(window).scrollTop() >= 500) {
$(".button").addClass('show');
} else {
$(".button").removeClass('show');
}
});
#wrapper {
width: 100%;
height: 2000px;
}
.button {
position: fixed;
bottom: 50px;
right: -100px;
/* You might still need prefixes here. Use as preferred. */
transition: right 500ms;
}
.button.show {
right: 0;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js"></script>
<div id="wrapper">
<div class="button">Here's my button!</div>
</div>
I've defined your button as hidden by default, by giving it a position of right: -100px. When we hit the correct scroll position, we add the class show and that triggers the animation performed by CSS and not javascript, as we have the transition property for the property right defined - that way the browser does the heavy lifting.

Toggling show/hide alters your elements width. You either have to put it in a container with display: inline
Or more ideally you might want to change show/hide to jQuery fadeIn() / fadeOut() which is more appropriate for "Back to Top" indicators.
Here is your codepen example modified with inline container:
http://codepen.io/anon/pen/MwWweY

Trigger event when user scroll to specific element - with jQuery

I have an h1 that is far down a page..
<h1 id="scroll-to">TRIGGER EVENT WHEN SCROLLED TO.</h1>
and I want to trigger an alert when the user scrolls to the h1, or has it in it's browser's view.
$('#scroll-to').scroll(function() {
alert('you have scrolled to the h1!');
});
how do I do this?

You can calculate the offset of the element and then compare that with the scroll value like:
$(window).scroll(function() {
var hT = $('#scroll-to').offset().top,
hH = $('#scroll-to').outerHeight(),
wH = $(window).height(),
wS = $(this).scrollTop();
if (wS > (hT+hH-wH)){
console.log('H1 on the view!');
}
});
Check this Demo Fiddle
Updated Demo Fiddle no alert -- instead FadeIn() the element
Updated code to check if the element is inside the viewport or not. Thus this works whether you are scrolling up or down adding some rules to the if statement:
if (wS > (hT+hH-wH) && (hT > wS) && (wS+wH > hT+hH)){
//Do something
}
Demo Fiddle

Combining this question with the best answer from jQuery trigger action when a user scrolls past a certain part of the page
var element_position = $('#scroll-to').offset().top;
$(window).on('scroll', function() {
var y_scroll_pos = window.pageYOffset;
var scroll_pos_test = element_position;
if(y_scroll_pos > scroll_pos_test) {
//do stuff
}
});
UPDATE
I've improved the code so that it will trigger when the element is half way up the screen rather than at the very top. It will also trigger the code if the user hits the bottom of the screen and the function hasn't fired yet.
var element_position = $('#scroll-to').offset().top;
var screen_height = $(window).height();
var activation_offset = 0.5;//determines how far up the the page the element needs to be before triggering the function
var activation_point = element_position - (screen_height * activation_offset);
var max_scroll_height = $('body').height() - screen_height - 5;//-5 for a little bit of buffer
//Does something when user scrolls to it OR
//Does it when user has reached the bottom of the page and hasn't triggered the function yet
$(window).on('scroll', function() {
var y_scroll_pos = window.pageYOffset;
var element_in_view = y_scroll_pos > activation_point;
var has_reached_bottom_of_page = max_scroll_height <= y_scroll_pos && !element_in_view;
if(element_in_view || has_reached_bottom_of_page) {
//Do something
}
});

I think your best bet would be to leverage an existing library that does that very thing:
http://imakewebthings.com/waypoints/
You can add listeners to your elements that will fire off when your element hits the top of the viewport:
$('#scroll-to').waypoint(function() {
alert('you have scrolled to the h1!');
});
For an amazing demo of it in use:
http://tympanus.net/codrops/2013/07/16/on-scroll-header-effects/

Inview library triggered event and works well with jquery 1.8 and higher!
https://github.com/protonet/jquery.inview
$('div').on('inview', function (event, visible) {
if (visible == true) {
// element is now visible in the viewport
} else {
// element has gone out of viewport
}
});
Read this https://remysharp.com/2009/01/26/element-in-view-event-plugin

Fire scroll only once after a successful scroll
Note: By successful scroll I mean when the user has scrolled to the desired
element or in other words when the desired element is in view
The accepted answer worked 90% for me so I had to tweak it a little to actually fire only once.
$(window).on('scroll',function() {
var hT = $('#comment-box-section').offset().top,
hH = $('#comment-box-section').outerHeight(),
wH = $(window).height(),
wS = $(this).scrollTop();
if (wS > ((hT+hH-wH)-500)){
console.log('comment box section arrived! eh');
// This detaches the scroll so doStuff() won't run more than once
$(window).off('scroll');
doStuff();
}
});

You could use this for all devices,
$(document).on('scroll', function() {
if( $(this).scrollTop() >= $('#target_element').position().top ){
do_something();
}
});

Intersection Observer can be the best thing IMO, without any external library it does a really good job.
const options = {
root: null,
threshold: 0.25, // 0 - 1 this work as a trigger.
rootMargin: '150px'
};
const target = document.querySelector('h1#scroll-to');
const observer = new IntersectionObserver(
entries => { // each entry checks if the element is the view or not and if yes trigger the function accordingly
entries.forEach(() => {
alert('you have scrolled to the h1!')
});
}, options);
observer.observe(target);

You can use jQuery plugin with the inview event like this :
jQuery('.your-class-here').one('inview', function (event, visible) {
if (visible == true) {
//Enjoy !
}
});
Link : https://remysharp.com/2009/01/26/element-in-view-event-plugin

This should be what you need.
Javascript:
$(window).scroll(function() {
var hT = $('#circle').offset().top,
hH = $('#circle').outerHeight(),
wH = $(window).height(),
wS = $(this).scrollTop();
console.log((hT - wH), wS);
if (wS > (hT + hH - wH)) {
$('.count').each(function() {
$(this).prop('Counter', 0).animate({
Counter: $(this).text()
}, {
duration: 900,
easing: 'swing',
step: function(now) {
$(this).text(Math.ceil(now));
}
});
}); {
$('.count').removeClass('count').addClass('counted');
};
}
});
CSS:
#circle
{
width: 100px;
height: 100px;
background: blue;
-moz-border-radius: 50px;
-webkit-border-radius: 50px;
border-radius: 50px;
float:left;
margin:5px;
}
.count, .counted
{
line-height: 100px;
color:white;
margin-left:30px;
font-size:25px;
}
#talkbubble {
width: 120px;
height: 80px;
background: green;
position: relative;
-moz-border-radius: 10px;
-webkit-border-radius: 10px;
border-radius: 10px;
float:left;
margin:20px;
}
#talkbubble:before {
content:"";
position: absolute;
right: 100%;
top: 15px;
width: 0;
height: 0;
border-top: 13px solid transparent;
border-right: 20px solid green;
border-bottom: 13px solid transparent;
}
HTML:
<div id="talkbubble"><span class="count">145</span></div>
<div style="clear:both"></div>
<div id="talkbubble"><span class="count">145</span></div>
<div style="clear:both"></div>
<div id="circle"><span class="count">1234</span></div>
Check this bootply:
http://www.bootply.com/atin_agarwal2/cJBywxX5Qp

If you are looking for a javascript version. You can call this method on scroll event listener.
showScrollTop = () =>{
const currentScrollPosition = window.pageYOffset;
let elementID = 'service-selector'
const elementOffsetTop = document.getElementById(elementID).offsetTop
if ( currentScrollPosition > elementOffsetTop){
// place your logic here
} else {
// place your logic here
}
}
window.addEventListener('scroll', showScrollTop)

If you are doing a lot of functionality based on scroll position, Scroll magic (http://scrollmagic.io/) is built entirely for this purpose.
It makes it easy to trigger JS based on when the user reaches certain elements when scrolling. It also integrates with the GSAP animation engine (https://greensock.com/) which is great for parallax scrolling websites

Just a quick modification to DaniP's answer, for anyone dealing with elements that can sometimes extend beyond the bounds of the device's viewport.
Added just a slight conditional - In the case of elements that are bigger than the viewport, the element will be revealed once it's top half has completely filled the viewport.
function elementInView(el) {
// The vertical distance between the top of the page and the top of the element.
var elementOffset = $(el).offset().top;
// The height of the element, including padding and borders.
var elementOuterHeight = $(el).outerHeight();
// Height of the window without margins, padding, borders.
var windowHeight = $(window).height();
// The vertical distance between the top of the page and the top of the viewport.
var scrollOffset = $(this).scrollTop();
if (elementOuterHeight < windowHeight) {
// Element is smaller than viewport.
if (scrollOffset > (elementOffset + elementOuterHeight - windowHeight)) {
// Element is completely inside viewport, reveal the element!
return true;
}
} else {
// Element is larger than the viewport, handle visibility differently.
// Consider it visible as soon as it's top half has filled the viewport.
if (scrollOffset > elementOffset) {
// The top of the viewport has touched the top of the element, reveal the element!
return true;
}
}
return false;
}

I use the same code doing that all the time, so added a simple jquery plugin doing it.
480 bytes long, and fast. Only bound elements analyzed in runtime.
https://www.npmjs.com/package/jquery-on-scrolled-to
It will be
$('#scroll-to').onScrolledTo(0, function() {
alert('you have scrolled to the h1!');
});
or use 0.5 instead of 0 if need to alert when half of the h1 shown.

Quick and fast implementation,
let triggered = false;
$(window).on('scroll',function() {
if (window.scrollY > ($('#scrollTo').offset().top+$('#scrollTo').outerHeight()-window.innerHeight) & !triggered){
console.log('triggered here on scroll..');
triggered = true;
}
});
using global variable triggered = false makes it just to happen once, otherwise, every time crossing past the element, this action is triggered.