I use the following code doing an action on scroll up or down.
var lastScrollTop = 0;
$(window).scroll(function(event){
var st = $(this).scrollTop();
if (st > lastScrollTop){
// downscroll code
} else {
// upscroll code
console.log("up");
}
lastScrollTop = st;
});
However, I only want to trigger it once.
Any idea of why the following version do not works?
Thanks !
var lastScrollTop = 0;
$(window).one('scroll',function(){
var st = $(this).scrollTop();
if (st > lastScrollTop){
// downscroll code
} else {
// upscroll code
console.log("up");
}
lastScrollTop = st;
});
If you want to check wether your handler has been called or not - you should define a flag(hasCalled in this case):
var lastScrollTop = 0;
$(window).scroll(function(event){
var st = $(this).scrollTop();
if(st <= lastScrollTop) {
console.log("up");
$(window).off('scroll');
}
lastScrollTop = st;
});
Related
I am new to programming and having an issue with my navigation bar. I have a fully functional nav bar and when I scroll down it hides as expected but does not pop back up when I scroll back up. This is the function I used for the scrolling:
var scrolled;
var lastscroll = 0;
var delta = 5;
var navHeight = $('header').outerHeight();
$(window).scroll(function(event){
scrolled = true;
});
setInterval(function() {
if (scrolled) {
hasScrolled();
scrolled = false;
}
}, 250);
function hasScrolled() {
var scrolltop = $(this).scrollTop();
if(Math.abs(lastscroll - scrolltop) <= delta)
return;
if (scrolltop > lastscroll && scrolltop > navHeight){
$('header').removeClass('nav-down').addClass('nav-up');
} else {
if(scrolltop + $(window).height() < $(document).height()) {
$('header').removeClass('nav-up').addClass('nav-down');
}
}
lastScrollTop = scrolltop;
}
Does anyone know what I am missing?
I have a function
$(document).ready(function () {
var lastScroll = 0;
$(window).scroll(function(event){
var st = $(this).scrollTop();
if ((lastScroll - st) == 5) {
$("header").css("position", "fixed");
}
else {
$("header").css("position", "absolute");
}
lastScroll = st;
});
});
But I want, when I scroll up on 5px, header again shows.
How I can follow event scroll up 5px?
You're updating your lastScroll too often, to make sure it has scrolled past a certain delta (in your case 5px) you should include that clause before checking if the user has scroll up or down.
This tutorial may help you, but I also created a fiddle with an updated version of your code.
But it would go like this:
$(document).ready(function () {
var lastScroll = 0;
$(window).scroll(function(event){
var st = $(this).scrollTop();
// Make sure they scroll more than delta
if(Math.abs(lastScroll - st) <= 5)
return;
if (st < lastScroll) {
$("header").css("position", "fixed");
} else {
$("header").css("position", "absolute");
}
lastScroll = st;
});
});
I have the following code which hides my menu when scrolls down, shows when scrolls up.
js
var didScroll;
var lastScrollTop = 0;
var delta = 5;
var navbarHeight = $('nav').outerHeight();
$(window).scroll(function(event) {
didScroll = true;
});
setInterval(function() {
if (didScroll) {
hasScrolled();
didScroll = false;
}
}, 250);
function hasScrolled() {
var st = $(this).scrollTop();
if (Math.abs(lastScrollTop - st) <= delta)
return;
if (st > lastScrollTop && st > navbarHeight ) {
// Scroll Down
$('nav').removeClass('nav-down').addClass('nav-up');
} else {
// Scroll Up
if (st + $(window).height() < $(document).height()) {
$('nav').removeClass('nav-up').addClass('nav-down');
}
}
lastScrollTop = st;
}
I would like it to hide and reveal in the same way but both scrolling up and down (it hides when you scroll either up or down then comes back down)
I am trying to stop a function when I click on a div "ego". The function displays or hides the header depending on the position of the scroll and should only work by default.
Here's my code:
$("#ego").click(function(e){
var $this = $(this);
if($this.data('clicked', false)){
hasScrolled();
}
e.stopPropagation();
});
var didScroll;
var lastScrollTop = 0;
var delta = 5;
var navbarHeight = $('header').outerHeight();
$(window).scroll(function(event){
didScroll = true;
});
setInterval(function() {
if (didScroll) {
hasScrolled();
didScroll = false;
}
}, 250);
function hasScrolled() {
var st = $(this).scrollTop();
// Make sure they scroll more than delta
if(Math.abs(lastScrollTop - st) <= delta)
return;
// If they scrolled down and are past the navbar, add class .nav-up.
// This is necessary so you never see what is "behind" the navbar.
if (st > lastScrollTop && st > navbarHeight){
// Scroll Down
$('header').animate({top:"-178px"}, 200, 'easeOutCubic');
} else {
// Scroll Up
if(st + $(window).height() < $(document).height()) {
$('header').animate({top:"0px"}, 200, 'easeOutCubic');
}
}
lastScrollTop = st;
}
Here's the fiddle:
https://jsfiddle.net/antoniobarcos/wL2vuv4h/2/
Any idea?
so if i get you right you want to stop hiding the navigation bar on top when you click a certain div:
you can achieve this by adding a class on click on the button to your #ego like stopNavigation. further you have to adjust your if clause where you set the top position of the header:
$("#ego").click(function(e){
var $this = $(this);
$this.toggleClass('stopNavigation');
});
and
if (st > lastScrollTop && st > navbarHeight && !$('#ego').hasClass('stopNavigation')){
// Scroll Down
$('header').animate({top:"-178px"}, 200);
}
i updated your fiddle for further information! i hope this is what you want to achieve: https://jsfiddle.net/wL2vuv4h/3/
Im using the following example to detect the direction of scrolling . However, it seems to operate on every scroll movement. Is there any way of getting it to operate only when the direction changes?
var lastScrollTop = 0;
$(window).scroll(function(event){
var st = $(this).scrollTop();
if (st > lastScrollTop){
// downscroll code
} else {
// upscroll code
}
lastScrollTop = st;
});
Sure. Just use a placeholder variable that keeps track of the last direction that was travelled, then return false if it is a match.
var lastScrollTop = 0;
var lastDirection = "";
$(window).scroll(function (event) {
var st = $(this).scrollTop();
if (st > lastScrollTop) {
lastScrollTop = st;
if (lastDirection === 'down') return false;
// downscroll code
console.log("scrolling down");
lastDirection = 'down';
} else {
lastScrollTop = st;
if (lastDirection === 'up') return false;
// upscroll code
console.log("scrolling up");
lastDirection = 'up';
}
});