I am aware this had been asked before, but no answer actually did the trick as far as I tested them.
Basically what I need is to change some element styles as soon as it "hits" the top border of the screen while scrolling down. This element is a 'Back to Top' button that will be sitting in a section and start following the user when they scroll pass said section.
I am not asking about CSS properties, I am asking about some JS property or method that allow me to know this. IE:
$('#back').distanceFromTopOfTheScreen() // This value will decrease as I scroll down
I know there are other soultions, but the client has asked for this behavior.
Any idea?
You can :
distance = $('#eleId')[0].getBoundingClientRect().top;
For more about getBoundingClientRect() look at the MDN Documentation
Note: This value change when you're scrolling, it gives you the distance between the top border of the element and the top of the Page
Sometimes JQuery make's everything more confusing than Native Javascript, even forgothing the very basics functions:
window.onscroll = function() { fixPosition()};
function fixPosition() {
var Yplus = 4; //number of lines in every scroll
document.getElementById('element').style.top = document.body.scrollTop + Yplus ;
}
This will allows you to move an "element" static on the window following the scroll.
Related
I’ve created an animation for my website to change a certain element (for example its background colour) while scrolling using Vanilla JS. For this I have used the window.onscroll property and I trigger the animation when window.scrollY reaches a specific position, my code is:
window.addEventListener('scroll', () => {
if (window.scrollX >= 1000) {
box.style = "background:red"
}
})
It looks great when I am editing on my big screen resolution, but if I look at the page on my laptop, the animation gets messed up because the innerWidth and innerHeight of the screen are different. I want to trigger the animation dynamically if it reaches a certain section of the page without having to worry about the scroll position.
Does anyone have any ideas about how I can fix this?
I think using getBoundingClientRect() solves your problem.
You basically do something like this:
var my_box = document.getElementById('my-box');
var rect = my_box.getBoundingClientRect();
The rect variable now contains an Object which includes a top and a left property with values that are relative to the viewport.
https://developer.mozilla.org/en-US/docs/Web/API/Element/getBoundingClientRect
In Jquery I'm aware you can move the scrollbars' starting location. Is this possible with pure javascript? To clarify, when the user loads the page I simply want the horizontal scrollbar to start scrolled all the way to the right, instead of starting at the left. If there are cross-browser issues, I'm particularly concerned with this working in Chrome.
document.body.scrollLeft = ( divRef.scrollWidth - divRef.offsetWidth ) / 2 ;
NOTE:
This can give odd results with IE8 and earlier.
I've made an example with a div, you can easily adjust this to your body tag, or another div, please see the demo.
var a = document.getElementById('body');
console.log(a.clientWidth)
function moveWin(a) {
window.scrollTo(a.clientWidth,0);
}
moveWin(a)
DEMO
SIDENOTE:
To select the body, simply use
var a = document.getElementsByTagName('body')[0]
This may come as a huge surprise to some people but I am having an issue with the IE browser when I am using the $(window).scroll method.
My goal:
I would like to have the menu located on the left retain it's position until the scroll reaches > y value. It will then fix itself to the top of the page until the scroll returns to a < y value.
My error:
Everything seems just fine in Chrome and Firefox but when I go to Internet Explorer it would seem the browser is moving #scroller every time the scroll value changes, this is causing a moving/flickering event.
If someone could point me to a resource or give me a workaround for this I would be very grateful!
Here is a fiddle:
http://jsfiddle.net/CampbeII/nLK7j/
Here is a link to the site in dev:
http://squ4reone.com/domains/ottawakaraoke/Squ4reone/responsive/index.php
My script:
$(window).scroll(function () {
var navigation = $(window).scrollTop();
if (navigation > 400) {
$('#scroller').css('top',navigation - 220);
} else {
$('#scroller').css('top',183);
$('#scroller').css('position','relative');
}
});
You might want to take a look at the jQuery Waypoints plugin, it lets you do sticky elements like this and a lot more.
If you want to stick with your current method, like the other answers have indicated you should toggle fixed positioning instead of updating the .top attribute in every scroll event. However, I would also introduce a flag to track whether or not it is currently stuck, this way you are only updating the position and top attributes when it actually make the transition instead of every scroll event. Interacting with the DOM is computationally expensive, this will take a lot of load off of the layout engine and should make things even smoother.
http://jsfiddle.net/WYNcj/6/
$(function () {
var stuck = false,
stickAt = $('#scroller').offset().top;
$(window).scroll(function () {
var scrollTop = $(window).scrollTop();
if (!stuck && scrollTop > stickAt) {
$('#scroller').css('top', 0);
$('#scroller').css('position','fixed');
stuck = true;
} else if (stuck && scrollTop < stickAt) {
$('#scroller').css('top', stickAt);
$('#scroller').css('position','absolute');
stuck = false;
}
});
});
Update
Switching the #scroller from relative to fixed removes it from the normal flow of the page, this can have unintended consequences for the layout as it re-flows without the missing block. If you change #scroller to use an absolute position it will be removed from the normal flow and will no longer cause these side-effects. I've updated the above example and the linked jsfiddle to reflect the changes to the JS/CSS.
I also changed the way that stickAt is calculated as well, it uses .offset() to find the exact position of the top of #scoller instead of relying on the CSS top value.
Instead of setting the top distance at each scroll event, please consider only switching between a fixed position and an absolute or relative position.All browsers will appreciate and Especially IE.
So you still listen to scroll but you now keep a state flag out of the scroll handler and simply evaluate if it has to switch between display types.
That is so much more optimized and IE likes it.
I can get flickers in Chrome as well if I scroll very quickly. Instead of updating the top position on scroll, instead used the fixed position for your element once the page has scrolled below the threshold. Take a look at the updated fiddle: http://jsfiddle.net/nLK7j/2/
Is there a way in javascript to bind an event handler to a horizontal scroll as opposed to the generic scroll event which is fired when the user scrolls horizontally and vertically? I want to trigger an event only when the user scrolls horizontally.
I searched around for an answer to this question, but couldn't seem to find anything.
Thanks!
P.S. My apologies if I'm using some terminology incorrectly. I'm fairly new to javascript.
UPDATE
Thanks so much for all your answers! In summary, it looks like you are all saying that this isn't supported in javascript, but I that I can accomplish the functionality with something like this (using jQuery) (jsFiddle):
var oldScrollTop = $(window).scrollTop();
$(window).bind('scroll', function () {
if (oldScrollTop == $(window).scrollTop())
//scrolled horizontally
else {
//scrolled vertically
oldScrollTop = $(window).scrollTop();
}
});
That's all I needed to know. Thanks again!
Answering from my phone, so unable to provide code at the moment.
What you'll need to do is subscribe to the scroll event. There isn't a specific one for vertical/horizontal.
Next, you'll need to get some measurements about the current display area. You'll need to measure the window.clientHeight and window.clientWidth.
Next, get window.top and window.left. This will tell you where position of the viewport is, ie if it's greater than 0 then scroll bars have been used.
It's pretty simple math from here to get what you need. If no one else has provided a code example in the next few hours I'll try to do so.
Edit:
A bit further information.
You must capture the scroll event. You also need to store the initial window.top and window.left properties somewhere. Whenever the scroll event happens, do a simple check to see if the current top/left values differ from the stores value.
At this point, if either are different you can trigger your own custom events to indicate vertical or horizontal scrolling. If you are using jQuery, this is very easy. If you are writing js without library assistance, it's easy too but a little more involved.
Do some searches for event dispatching in js.
You can then write any other code you want to subscribe to your custom events without needing to tie them together with method calls.
I wrote a jQuery plugin for you that lets you attach functions to the scrollh event.
See it in action at jsfiddle.net.
/* Enable "scrollh" event jQuery plugin */
(function ($) {
$.fn.enableHScroll = function() {
function handler(el) {
var lastPos = el
.on('scroll', function() {
var newPos = $(this).scrollLeft();
if (newPos !== lastPos) {
$(this).trigger('scrollh', newPos - lastPos);
lastPos = newPos;
}
})
.scrollLeft();
}
return this.each(function() {
var el = $(this);
if (!el.data('hScrollEnabled')) {
el.data('hScrollEnabled', true);
handler(el);
}
});
}
}(jQuery));
It's this easy to use:
$('#container')
.enableHScroll()
.on('scrollh', function(obj, offset) {
$('#info').val(offset);
});
Please note that scroll events come very fast. Even if you click in the scrollbar to jump to a new position, many scroll events are generated. You may want to adjust this code to wait a short time and accumulate all the changes in position during that time before firing the hscroll event.
You can use the same scroll event, but within your handler use the scrollLeft function to see if the scrollbar moved horizontally from the last time the event was fired. If the scrollbar did not move then just return from your handler. Otherwise update your variable to the new position and take action.
You can check if the the x value of the page changes and ignore your y value.
If the x value changes: There is your horizontal scroll.
With page-load, store the initial scrollbar positions for both in two variables (presumably both will be 0). Next, whenever a scroll event occurs, find the scrollleft and scrolltop properties. If the scrollleft property's value is different and scrolltop's value is same as compared to their earlier values, that's a horizontal scroll. Then set the values of the variables to the new scroll values.
No, there is no special event for scroll horizontal (it is for global scroll), but you can try to check the position of content by property .scrollLeft and if it's different from the previous value it means that the user scrolled content horizontally.
This is a followup question for this:
Scrollpane on the bottom, css is hacky, javascript is hard
I ended up doing the scrolling in the same way explained in the accepted answer.
Now there is a request that one item is selected somehow (eg. as an url parameter or by some javascript calls) I should scroll the pane to the item with the corresponding ID in the scrollpane. Like a link to an anchor () would work!
I want to make a javascript call like this
function scrollTo(id) {
$('#middle').magicallyScrollThatItemWouldBeVisible(itemid);
}
But this is not in jQuery (or at least I don't know of it). So is there a way to make it?
I'll post a simple jsFiddle here:
http://jsfiddle.net/ruisoftware/U6QdQ/4/
Help me write that scrollTo function!
A .animate would be fine too.
UPDATE: If it was not clear I would like it to only align to the left or right side of the panel, it it was overflowed on that side (so the minimum possible amount of scrolling happens)
It's not jQuery, just JavaScript, and I've actually never used it all, so I'm not sure how you would have to mess with it to get it to work in this situation, but there is a scrollIntoView function:
yourElement.scrollIntoView();
Since the elements have a fixed width, you can count the number of elements by using .index() + 1, and animate to this value (after subtracting the container's width).
If you want the element to be centered, use - Math.round(middle.width()/100)*50.
Fiddle: http://jsfiddle.net/U6QdQ/17/
//This code should be run on load / DOMReady
(function($){ //Run on load / DOMReady
$.fn.magicScrollTo = function(){
var middle = $("#middle");
var currentScrollLeft = middle.scrollLeft();
var width = middle.width();
var newScrollLeft = this.offset().left + currentScrollLeft - middle.offset().left;
if(newScrollLeft >= currentScrollLeft && newScrollLeft <= currentScrollLeft + width - this.outerWidth()) return;
if(newScrollLeft > currentScrollLeft){ //If the element is at the right side
newScrollLeft = newScrollLeft - width + this.outerWidth();
}
middle.animate({
scrollLeft: newScrollLeft,
}, 'fast')
}
})(jQuery);
Usage:
//Select the 4rd element, and scroll to it (eq is zero-based):
$('.item').eq(3).magicScrollTo();
Something along these lines would be a good start:
http://jsfiddle.net/vHjJ4/
This will bring the target into the centre of the carousel. I think you will have to add in some extra checks to make sure that it didn't scroll to far, for example if you targeted the first or last element...unless this is built into the scroll function (it might be).
I'm not sure I understand your question exactly, but it sounds like you're asking how to scroll horizontally to the selected item in the bottom pane. If so, try something like this:
//get the position of the element relative to the parent ("middle")
var pos = $("#itemid").position();
if (pos){
$("#middle").scrollLeft(pos.left);
}
From here, you can use the width of middle to center the item if needed.