i have 4 offset().top values that i would like updated when i resize the page. i have each value stored as a variable to use with a scrolling animation and css style changes as you scroll down. here is a bit of the code:
var top1 = $('#home').offset().top;
var top2 = $('#profile').offset().top;
var top3 = $('#portfolio').offset().top;
var top4 = $('#contact').offset().top;
$(document).scroll(function () {
var scrollPos = $(document).scrollTop();
if (scrollPos >= top1 && scrollPos < top2) {
$('.nav-bar').css({
'background-color': 'rgba(255, 255, 255, 0.7)',
'color': '#203B40'
});
$("#homeLink").click(function () {
$("html, body").animate({
scrollTop: top1
}, 500);
});
$("#profileLink").click(function () {
$("html, body").animate({
scrollTop: top2 + 8
}, 500);
});
for now, if i manually refresh the page after resize everything matches up fine, on any size. However, if i change the page size without refreshing, the links no longer match up.
i have played around with $(window).resize and window.addEventListener('resize', function) but don't know how to properly use them. i have spent the last three nights scouring google and playing with (breaking) my code. Maybe I just need to reset my variable values on resize, or i have to reset the entire page. i am not sure the best way to deal with this.
here is my codepen with the code. i didnt add the photos or bg imgs. but all the code is there. Thanks for any and all help. https://codepen.io/efe-in-the-mountains/pen/dJLaqK?editors=0010
You need to change your top1,top2,top3,top4 variable when $(window).resize is triggered. Add the snippet below and see if the code is doing what I think you want to do.
$(window).resize(function () {
top1 = $('#home').offset().top;
top2 = $('#profile').offset().top;
top3 = $('#portfolio').offset().top;
top4 = $('#contact').offset().top;
});
Read more here https://developer.mozilla.org/en-US/docs/Web/Events/resize to understand when the resize event is triggered.
Related
I've got a back to top button that shows up on my webpage that I'm working on. When you scroll down and sometimes when it's clicked it jumps to the top and then jumps back to where you were on the page and then smoothly scrolls to the top like it's supposed to. Keep in mind that it does not do this all the time. Would this just be a lag or glitch issue or if there some error in my script?
$(function(){
$(document).on( 'scroll', function(){
if ($(window).scrollTop() > 615) {
$('.ion-android-arrow-dropup-circle').addClass('show');
} else {
$('.ion-android-arrow-dropup-circle').removeClass('show');
}
});
$('.ion-android-arrow-dropup-circle').on('click', scrollToTop);
});
function scrollToTop() {
verticalOffset = typeof(verticalOffset) != 'undefined' ? verticalOffset : 0;
element = $('body');
offset = element.offset();
offsetTop = offset.top;
$('html, body').animate({scrollTop: offsetTop}, 500, 'linear');
};
Searched 40+ questions and couldn't find an answer. Only saying this because if you don't and somebody finds one they always say, "You should have looked before asking." I see it all the time.
ANSWER TO MY OWN QUESTION
After going so long without responses I had moved on and decided not to worry about this issue at that time. Today, I was working on a different site using the same jQuery script and was having the same problem. I decided to try and fix it myself since I couldn't find help on the issue.
The solution was simple! I don't know how I missed it the first time around. All I did is take the above code and add one function to it:
$('.ion-android-arrow-dropup-circle').click(function(event) {
event.preventDefault()
});
I forgot all about needing to remove the default action of clicking a link which is jumping to the destination. It now works perfectly smooth and looks great, just like I wanted to begin with!
My fully updated script for your reference:
$(function(){
$(document).on( 'scroll', function(){
if ($(window).scrollTop() > 50) {
$('.ion-eject').addClass('show');
} else {
$('.ion-eject').removeClass('show');
}
});
$('.ion-eject').click(function(event) {
event.preventDefault()
});
$('.ion-eject').on('click', scrollToTop);
});
function scrollToTop() {
verticalOffset = typeof(verticalOffset) != 'undefined' ? verticalOffset : 0;
element = $('body');
offset = element.offset();
offsetTop = offset.top;
$('html, body').animate({scrollTop: offsetTop}, 200, 'linear');
};
I'm working on an info screen that displays a table of informations which usually is quite long, so I want it to scroll slowly down automatically until it reaches the bottom, fades to white, scroll back up, and fades out from white, repeating the process all over after some delays.
Currently I have this code:
var iInterval = 2000;
var iScrollInterval = 5000;
var iFadeInterval = 500;
var loop = function() {
var iScroll = $(document).height() - $(window).height();
$("html, body").animate({
scrollTop: iScroll
}, {
duration : iScrollInterval,
easing : "linear",
complete : function() {
$("body").fadeOut(iFadeInterval).delay(iFadeInterval);
$("html, body").scrollTop(0);
$("body").fadeIn(iFadeInterval);
}
});
setTimeout(loop, iInterval);
};
setTimeout(loop, iInterval);
The problem with that code is that scrolls down to the bottom, immediately jumps to the top again, without fading and keeps scrolling down immediately without delay.
This behavior is repeating 2-3 times until, finally, the fading to/from white happens, once the bottom of the page is reached for the 3rd time.
There's no doubt I've misunderstood something here, but what?
I haven't been using jQuery for a while, but after looking at your code there is couple of things:
Why are you scrolling both HTML and BODY?
The page jumps back up because you are not animating it here:
$("html, body").scrollTop(0);
And al other problems derive from that. If I have a minute I will update my answer with fiddle
Fiddle:
http://jsfiddle.net/64etqaxc/1/
var iInterval = 2000;
var iScrollInterval = 5000;
var iFadeInterval = 500;
var loop = function() {
var iScroll = $(document).height() - $(window).height();
$("html").animate({
scrollTop: iScroll
}, {
duration : iScrollInterval,
easing : "linear",
complete : function() {
$("body").fadeOut(iFadeInterval, function(){
$("html").scrollTop(0);
$("body").fadeIn(iFadeInterval,function(){
loop();
});
});
}
});
};
loop();
I'm having troubles getting this code to execute in a timely manner in Firefox. It seems to work just fine in Chrome.
JSFiddle here: http://jsfiddle.net/EXDhb/
Real live example page I'm working with here: http://mindevo.com/tests/tacos.html
I'm not sure if I'm leaving something out. I kind of hacked this together from reading a bunch of page-scroll scripts other people have put together. Not sure if this is even the best way for me to do what I'm trying to accomplish (which is to darken the next area until it's somewhat revealed. (I used halfway for this).
Here's my javascript:
$(document).ready(function(){
$(window).scroll(function(){
$('.dark').each(function(i){
var half_object = $(this).position().top + ($(this).outerHeight()/2);
var bottom_window = $(window).scrollTop() + $(window).height();
var bottom_object = $(this).position().top + $(this).outerHeight();
if(bottom_window > half_object){
$(this).animate({'opacity':'1'},200);
}
else if(bottom_object > $(window).scrollTop()) {
$(this).animate({'opacity':'.5'},200);
}
});
});
});
Is there a better way to do this? I tried adding/removing css classes but it invoked some crazy Chrome bug I was not pleased about.
Why does it work so slowly in Firefox?
Start by not having 6 separate jQuery $(this) operations and multiple $(window)! Use temp variables whenever you can to avoid requerying.
JSFIddle: http://jsfiddle.net/TrueBlueAussie/EXDhb/9/
$(document).ready(function () {
// window never changes
var $window = $(window);
$window.scroll(function () {
// Window height may have changed between scrolls
var windowHeight = $window.height();
var scrollTop = $window.scrollTop();
$('.dark').each(function (i) {
var $this = $(this);
var top = $this.position().top;
var outerH = $this.outerHeight();
var half_object = top + (outerH / 2);
var bottom_window = scrollTop + windowHeight;
var bottom_object = top + outerH;
console.log(half_object);
if (bottom_window > half_object) {
$this.stop().animate({
'opacity': '1'
}, 200);
} else if (bottom_object > scrollTop) {
$this.stop().animate({
'opacity': '.5'
}, 200);
}
});
});
});
And so on until you do not do anything twice that has an overhead that you do not need to have.
Update: Stop previous animations
The pause was not caused by the speed of the code above, but by not stopping multiple animations. The problem is that scroll fires frequently, so without .stop() animations get queued up and fire one after the other. This made it look much slower that it actually was.
Further optimizations might involve only processing elements that are actually onscreen, but that is pretty pointless given the apparent speed now.
You can cache your variables, which should help slightly:
$(document).ready(function(){
var $window = $(window);
$window.scroll( function(){
$('.dark').each(function(i){
var $this = $(this);
var outerHeight = $this.outerHeight();
var positionTop = $this.position().top;
var half_object = positionTop + (outerHeight/2);
var bottom_window = window.scrollTop() + window.height();
var bottom_object = positionTop + outerHeight;
if(bottom_window > half_object){
$this.animate({'opacity':'1'}, 200);
} else if(bottom_object > window.scrollTop()) {
$this.animate({'opacity':'.5'}, 200);
}
});
});
});
I realize there is already an accepted answer, but many times it is useful to do something only after the user has stopped scrolling, and not each time the "scroll" event fires. This event can can fire upwards of 50 times per second, leaving you with ~20ms to do what you need to do. This other StackOverflow question shows you how to do something only after scrolling has stopped. As #TrueBlueAussie mentioned in his answer, you would still want to stop any animations that were currently running.
I'm using the following javascript for the top of page logo/section before the footer here:
<div id="townEnd">InsideTown</div>
<script>
$(document).ready(function(){
// hide #townEnd first
$("#townEnd").hide();
// fade in #townEnd
$(function () {
$(window).scroll(function () {
if ($(this).scrollTop() > 1000) {
$('#townEnd').fadeIn();
} else {
$('#townEnd').fadeOut();
}
});
// scroll body to 0px on click
$('#townEnd a').click(function () {
$('body,html').animate({
scrollTop: 0
}, 800);
return false;
});
});
});
</script>
How would I calculate when the logo should fadein at the end of the page? I just used 1000 as an example. It only seems to work when I scroll really fast too.
First, you should just use this.scrollTop instead of $(this).scrollTop() - it might not look like much to you, but it is a HUGE thing.
On the same path, you can use this.scrollHeight to get the height of the scrollable area. Subtract this.innerHeight to get the maximum scroll position, then subtract about 30 pixels to give yourself some padding.
if( this.scrollTop < this.scrollHeight - this.innerHeight - 30)
You should also have a boolean to keep track of the state of the element, maybe isfadedin, which you update. Then, only call fadeIn and fadeOut if the state changes. This will save a LOT of processing time!
Vanilla JS is awesome :p
I have an HTML document with images in a grid format using <ul><li><img.... The browser window has both vertical & horizontal scrolling.
Question:
When I click on an image <img>, how then do I get the whole document to scroll to a position where the image I just clicked on is top:20px; left:20px ?
I've had a browse on here for similar posts...although I'm quite new to JavaScript, and want to understand how this is achieved for myself.
There's a DOM method called scrollIntoView, which is supported by all major browsers, that will align an element with the top/left of the viewport (or as close as possible).
$("#myImage")[0].scrollIntoView();
On supported browsers, you can provide options:
$("#myImage")[0].scrollIntoView({
behavior: "smooth", // or "auto" or "instant"
block: "start" // or "end"
});
Alternatively, if all the elements have unique IDs, you can just change the hash property of the location object for back/forward button support:
$(document).delegate("img", function (e) {
if (e.target.id)
window.location.hash = e.target.id;
});
After that, just adjust the scrollTop/scrollLeft properties by -20:
document.body.scrollLeft -= 20;
document.body.scrollTop -= 20;
Since you want to know how it works, I'll explain it step-by-step.
First you want to bind a function as the image's click handler:
$('#someImage').click(function () {
// Code to do scrolling happens here
});
That will apply the click handler to an image with id="someImage". If you want to do this to all images, replace '#someImage' with 'img'.
Now for the actual scrolling code:
Get the image offsets (relative to the document):
var offset = $(this).offset(); // Contains .top and .left
Subtract 20 from top and left:
offset.left -= 20;
offset.top -= 20;
Now animate the scroll-top and scroll-left CSS properties of <body> and <html>:
$('html, body').animate({
scrollTop: offset.top,
scrollLeft: offset.left
});
Simplest solution I have seen
var offset = $("#target-element").offset();
$('html, body').animate({
scrollTop: offset.top,
scrollLeft: offset.left
}, 1000);
Tutorial Here
There are methods to scroll element directly into the view, but if you want to scroll to a point relative from an element, you have to do it manually:
Inside the click handler, get the position of the element relative to the document, subtract 20 and use window.scrollTo:
var pos = $(this).offset();
var top = pos.top - 20;
var left = pos.left - 20;
window.scrollTo((left < 0 ? 0 : left), (top < 0 ? 0 : top));
Have a look at the jQuery.scrollTo plugin. Here's a demo.
This plugin has a lot of options that go beyond what native scrollIntoView offers you. For instance, you can set the scrolling to be smooth, and then set a callback for when the scrolling finishes.
You can also have a look at all the JQuery plugins tagged with "scroll".
Here's a quick jQuery plugin to map the built in browser functionality nicely:
$.fn.ensureVisible = function () { $(this).each(function () { $(this)[0].scrollIntoView(); }); };
...
$('.my-elements').ensureVisible();
After trial and error I came up with this function, works with iframe too.
function bringElIntoView(el) {
var elOffset = el.offset();
var $window = $(window);
var windowScrollBottom = $window.scrollTop() + $window.height();
var scrollToPos = -1;
if (elOffset.top < $window.scrollTop()) // element is hidden in the top
scrollToPos = elOffset.top;
else if (elOffset.top + el.height() > windowScrollBottom) // element is hidden in the bottom
scrollToPos = $window.scrollTop() + (elOffset.top + el.height() - windowScrollBottom);
if (scrollToPos !== -1)
$('html, body').animate({ scrollTop: scrollToPos });
}
My UI has a vertical scrolling list of thumbs within a thumbbar
The goal was to make the current thumb right in the center of the thumbbar.
I started from the approved answer, but found that there were a few tweaks to truly center the current thumb. hope this helps someone else.
markup:
<ul id='thumbbar'>
<li id='thumbbar-123'></li>
<li id='thumbbar-124'></li>
<li id='thumbbar-125'></li>
</ul>
jquery:
// scroll the current thumb bar thumb into view
heightbar = $('#thumbbar').height();
heightthumb = $('#thumbbar-' + pageid).height();
offsetbar = $('#thumbbar').scrollTop();
$('#thumbbar').animate({
scrollTop: offsetthumb.top - heightbar / 2 - offsetbar - 20
});
Just a tip. Works on firefox only
Element.scrollIntoView();
Simple 2 steps for scrolling down to end or bottom.
Step1: get the full height of scrollable(conversation) div.
Step2: apply scrollTop on that scrollable(conversation) div using the value
obtained in step1.
var fullHeight = $('#conversation')[0].scrollHeight;
$('#conversation').scrollTop(fullHeight);
Above steps must be applied for every append on the conversation div.
After trying to find a solution that handled every circumstance (options for animating the scroll, padding around the object once it scrolls into view, works even in obscure circumstances such as in an iframe), I finally ended up writing my own solution to this. Since it seems to work when many other solutions failed, I thought I'd share it:
function scrollIntoViewIfNeeded($target, options) {
var options = options ? options : {},
$win = $($target[0].ownerDocument.defaultView), //get the window object of the $target, don't use "window" because the element could possibly be in a different iframe than the one calling the function
$container = options.$container ? options.$container : $win,
padding = options.padding ? options.padding : 20,
elemTop = $target.offset().top,
elemHeight = $target.outerHeight(),
containerTop = $container.scrollTop(),
//Everything past this point is used only to get the container's visible height, which is needed to do this accurately
containerHeight = $container.outerHeight(),
winTop = $win.scrollTop(),
winBot = winTop + $win.height(),
containerVisibleTop = containerTop < winTop ? winTop : containerTop,
containerVisibleBottom = containerTop + containerHeight > winBot ? winBot : containerTop + containerHeight,
containerVisibleHeight = containerVisibleBottom - containerVisibleTop;
if (elemTop < containerTop) {
//scroll up
if (options.instant) {
$container.scrollTop(elemTop - padding);
} else {
$container.animate({scrollTop: elemTop - padding}, options.animationOptions);
}
} else if (elemTop + elemHeight > containerTop + containerVisibleHeight) {
//scroll down
if (options.instant) {
$container.scrollTop(elemTop + elemHeight - containerVisibleHeight + padding);
} else {
$container.animate({scrollTop: elemTop + elemHeight - containerVisibleHeight + padding}, options.animationOptions);
}
}
}
$target is a jQuery object containing the object you wish to scroll into view if needed.
options (optional) can contain the following options passed in an object:
options.$container - a jQuery object pointing to the containing element of $target (in other words, the element in the dom with the scrollbars). Defaults to the window that contains the $target element and is smart enough to select an iframe window. Remember to include the $ in the property name.
options.padding - the padding in pixels to add above or below the object when it is scrolled into view. This way it is not right against the edge of the window. Defaults to 20.
options.instant - if set to true, jQuery animate will not be used and the scroll will instantly pop to the correct location. Defaults to false.
options.animationOptions - any jQuery options you wish to pass to the jQuery animate function (see http://api.jquery.com/animate/). With this, you can change the duration of the animation or have a callback function executed when the scrolling is complete. This only works if options.instant is set to false. If you need to have an instant animation but with a callback, set options.animationOptions.duration = 0 instead of using options.instant = true.