Develop Reference

How to detect when the scroll starts using Javascript/Jquery?

I want to make a one pager website, without using any third party libraries, like FullPage.js.
when scroll starts --> instead of waiting for the end of the natural scrolling, I want it to take no effect (so no visible scroll caused by the mouse) and to run my code instead. (so it could always go to next section, or previous one, without relying on the amount of the users scroll)
Do you have any idea how could I achieve this? My code snippet waits for the end of scroll, and then jumps to where it should, so it's not working as intended.
(the first section has a "current" class and then the code snippet works by manipulating the 100vh sections by adding/removing this class)
You can see the code snippet I am using below or here:
https://codepen.io/makiwara/pen/PoqjdNZ
Thank you very much for your help, have a nice day!
var script = document.createElement('script');script.src = "https://code.jquery.com/jquery-3.4.1.min.js";document.getElementsByTagName('head')[0].appendChild(script);
var timerId;
var scrollableElement = document.body; //document.getElementById('scrollableElement');
scrollableElement.addEventListener('wheel', checkScrollDirection);
function checkScrollDirection(event) {
var $current = $('.current');
if (checkScrollDirectionIsUp(event)) {
console.log('UP');
$prev = $current.prev();
if ($prev.length) {
clearTimeout(timerId);
timerId = setTimeout(function(){
$current.removeClass('current');
$prev.addClass('current');
$('body,html').animate({
scrollTop: $('.current').offset().top
}, 100);
}, 100)
}
} else {
console.log('Down');
$next = $current.next();
if ($next.length) {
clearTimeout(timerId);
timerId = setTimeout(function(){
$current.removeClass('current');
$next.addClass('current');
$('body,html').animate({
scrollTop: $('.current').offset().top
}, 100);
} , 100)
}
}
}
function checkScrollDirectionIsUp(event) {
if (event.wheelDelta) {
return event.wheelDelta > 0;
}
return event.deltaY < 0;
}

What you need is throttling the event listener, i.e. limit a function call only once per a time period.
What your code is doing is essentially debouncing i.e limit a function call only after a wait time period has passed.
Firstly ditch the timers you're using. You need to somehow block scrolling from happening more than once. The JavaScript part can be easy if you use Underscore.js's throttle function with one caveat though: It passes through subsequent events after the time period has passed. Luckily, its debouncing method accepts a third argument that gives the behavior you'd want:
scrollableElement.addEventListener(
"wheel",
_.debounce(checkScrollDirection, 200, true) // immediately call the function _once_
);
This third argument makes the debounced function behave like a throttled one, that is it will fire only once and at the same time it will fire immediately.
So assuming that your event handler is now free from the original timeout
function checkScrollDirection(event) {
var $current = $(".current");
if (checkScrollDirectionIsUp(event)) {
console.log("UP");
$prev = $current.prev("section");
if ($prev.length) {
$current.removeClass("current");
$prev.addClass("current");
$("body,html").animate(
{
scrollTop: $prev.offset().top
},
100
);
}
} else {
console.log("Down");
$next = $current.next("section");
if ($next.length) {
$current.removeClass("current");
$next.addClass("current");
$("body,html").animate(
{
scrollTop: $next.offset().top
},
100
);
}
}
}
btw, try to get into the habit of specifying selectors inside .next() and .prev() since jQuery will match all possible siblings, which most likely you don't want. In this case, codepen appends additional <script> elements and jQuery will match those as well.
Now if you try this, you'll notice that the window still responds to every scroll event. Scroll events are one of those events that cannot be cancelled so you need to disable it via CSS
The easiest way is to hide the overflow of the body
body { max-height: 100vh; overflow: hidden; }
And that's it. You may need to adjust the throttle waiting time period to match your preferences.
You can find a working version of the codepen here: https://codepen.io/vassiliskrikonis/pen/XWbgxLj

.delay() not working on my .show() JQuery

I'm trying to make my footer disappear when on a mobile device and only when the keyboard is open. Which I have working perfectly, however the issue is that the footer reappears before the keyboard has time to close. Which is because I'm using the event from the textbox having focus not the keyboard being open. So I thought the best way to resolve this is with a .delay() however, this isn't working at all. Anyone have any ideas here?
<script>
var isMobileView = false; //global variable
$(document).ready(function () {
function setScreenWidthFlag() {
var newWindowWidth = $(window).width();
if ( $(window).width() > 600) {
isMobileView = false;
}
else {
isMobileView = true;
}
}
$(".tbinputArea").focus(function() {
if(isMobileView)
$("#footer").hide();
});
$(".tbinputArea").focusout(function() {
if(isMobileView)
$("#footer").delay(500).show();
});
setScreenWidthFlag();
$(window).on("resize", function (e) {
setScreenWidthFlag();
});
});
</script>

$("#footer").delay(500).show(0);
Try this.

refer this explanation precisely explained the reasons for it http://www.mattlunn.me.uk/blog/2012/06/jquery-delay-not-working-for-you/
Delay is just for queue delay not any event delay so try to add some events within like fadeIn or similar.

Switch click and hover events based on width

I want to toggle events based on width. for mobile only click event should work. for desktop hover event should work. while page loading my code working properly when resize my code is not working.
please help me why my code is not working. Thanks in advance
$(document).ready(function(){
function forDesktop(){
$(".popover-controls div").off('click');
$(".popover-controls div").on('hover');
$(".popover-controls div ").hover(function(e){
//popup show code
});
}
function forMobile(){
console.log("mobile");
$(".popover-controls div").off('hover');
$(".popover-controls div").on('click');
$(".popover-controls div").click(function(e){
//popop show
});
}
function process(){
$(window).width() > 600?forDesktop():forMobile();
}
$(window).resize(function(){
process()
});
process();
});

Its very simple, 1st you cant write this much of code for every event. We have to come up with very simple solution, here is how it works
1st check the width of the Page in JS and assign Desktop/Mobile Class on body :
function process(){
if( $(window).width() > 600){
$("body").removeClass("mobile").addClass("desktop");
}else{
$("body").removeClass("desktop").addClass("mobile");
}
}
$(window).resize(function(){
process()
});
Now, you have execute the command for hover and click:
$(document).on('mouseover', 'body.mobile .popover-controls div',function(e){
alert("hover");
});
$(document).on('click', 'body.desktop .popover-controls div',function(e){
alert("click");
console.log("click");
});
I Hope this will work for you. :)
Check the Js fiddle Example: http://jsfiddle.net/asadalikanwal/xcj8p590/
I have just created for you, also i have modified my code

You could use a JavaScript Media Query to determine the width of the screen as detailed here.
var mq = window.matchMedia( "(min-width: 500px)" );
The matches property returns true or false depending on the query result, e.g.
if (mq.matches) {
// window width is at least 500px
} else {
// window width is less than 500px
}

First Detect the Mobiles/Tablets Touch Event:
function is_touch_device() {
return 'ontouchstart' in window // works on most browsers
|| 'onmsgesturechange' in window; // works on ie10
};
Then Try like this:
function eventFire() {
var _element = $(".popover-controls div");
// True in Touch Enabled Devices
if( is_touch_device() ) {
_element.click(function(e) { .... });
}
else {
// apply Hover Event
_element.hover();
}
}
No need to detect width of devices ;)
There is one more solution with third party and Most popular library is Modernizr

This worked for me. It's a combination of the matchMedia() functionality #Ḟḹáḿíṅḡ Ⱬỏḿƀíé shared as well setTimeout() functionality #Jeff Lemay shared at TeamTreeHouse.com
The primary thing I contributed to was the use of the .unbind() functionality. It took me quite a while to figure out that this was necessary so the .hover() and .click() functions don't cross wires.
//Add/remove classes, in nav to show/hide elements
function navClassHandler(){
if($(this).hasClass('active')){
$('.dropdown').removeClass('active');
}else{
$('.dropdown').removeClass('active');
$(this).addClass('active');
}
}
function handleNav() {
//instantanteous check to see if the document matches the media query.
const mqM = window.matchMedia('(max-width: 1025px)');
const mqD = window.matchMedia('(min-width: 1025px)');
$('.dropdown').unbind(); //necessary to remove previous hover/click event handler
if (mqM.matches) {
console.log("Handling mobile");
$('.dropdown').click(navClassHandler);
} else {
console.log("Handling desktop");
$('.dropdown').hover(navClassHandler);
}
}
// we set an empty variable here that will be used to clearTimeout
let id;
/* this tells the page to wait half a second before making any changes,
we call our handleNav function here but our actual actions/adjustments are in handleNav */
$(window).resize(function() {
clearTimeout(id);
id = setTimeout(handleNav, 500);
});
//As soon as the document loads, run handleNav to set nav behavior
$(document).ready(handleNav);

Multiple functions for mouse events jquery

I'm working on a jQuery plugin. To separate my logic I do something like this:
$element.on({
mouseenter: function(){
//do something special
}, mouseleave: function(){
//do something else special
}
});
//more stuffs
and then above this I do that again but with other function body
$element.on({
mouseenter: function(){
//do something not special
}, mouseleave: function(){
//do something else not special
}
});
How does jQuery deal with this ? Will 2nd declaration of mouse events function override the first one ? Sometimes I see both things works but sometimes not.

Will 2nd declaration of mouse events function override the first one ?
No.
How does jQuery deal with this ?
It executes your event handlers in the order in which they were attached. From the documentation (about 40% down the page):
Event handlers bound to an element are called in the same order that they were bound.
So for instance, if you have:
var div = $("#someDiv");
div.on("click", function() { console.log("one"); });
div.on("click", function() { console.log("two"); });
div.on("click", function() { console.log("three"); });
...then clicking the div will give you
one
two
three
...in the console.
Note that it doesn't matter how you found the element to attach the handlers. Let's say you have only one div on the page, it has the id "someDiv", and it's the first child of body (just to make the selectors easy). If you have:
$("#someDiv").on("click", function() { console.log("one"); });
$(document.body).children().first().on("click", function() { console.log("two"); });
$("div").on("click", function() { console.log("three"); });
and you click the div, you'll get
one
two
three
...in the console.

Resize script appends object, does it over and over again

I have the following code in a JavaScript file:
$(document).ready(function() {
detectscreen();
});
$(window).resize(function(){
detectscreen();
});
function windowWidth() {
if(!window.innerWidth) {
// user is being a git, using ie
return document.documentElement.clientWidth;
} else {
return window.innerWidth;
}}
function detectscreen() {
if (windowWidth()>1280) {
$('body').append('<div id="gearsfloat"></div>');
}}
Basically, what it does is append an object to the end of the document if the width is less than 1280 pixels, however what this does is append it every single time the page is resized.
I don't think I can use the once function because it would only run it once and then the next time it is resized, it's dead. Anything I can do?
NOTE: I, in fact, DO want it to be checked on the resize of the page, but the effect is that it happens over and over again.
if (windowWidth()>1280 && !$('gearsfloat')) {
$('body').append('<div id="gearsfloat"></div>');
}
The above (by Jason) works does not work but then it won't delete it when it gets less than 1280. Is there anything I can do?

Keep track of whether the element exists or not, and add/remove it when the condition changes. That way you will only add it once, it will be removed when it shouldn't be there, and you don't do any unneccesary adding or removing:
var gearsExists = false;
function detectscreen() {
var shouldExist = windowWidth() > 1280;
if (shouldExist != gearsExists) {
if (shouldExist) {
$('body').append('<div id="gearsfloat"></div>');
} else {
$('#gearsfloat').remove();
}
gearsExists = shouldExist;
}
}

if (windowWidth()>1280 && !$('gearsfloat')) {
$('body').append('<div id="gearsfloat"></div>');
}
Check if the element already exists first?

if you dont want the function to be called when the window is resized, then why are you binding the resize function?
wont the document ready function always be called before the resize function anyway, so you are guaranteed to have your element appended?