Develop Reference

Check if whole div is visible in browser window

I have a product listing on my website and when hovering over the product an info div shows up. The only problem is that in some cases parts of the div fall outside of the browser window.
I need to check with Javascript if thats the case, and if so I need to assign a class to that particular div. I know how to do the last part, but I have no idea how to check if the whole div is visible.
Can anybody give me a suggestion how to handle this?

Your goal is to determine if your HTML element is in the viewport. If you're using jQuery - there are a few plugins tha handle this.
Jquery check if element is visible in viewport
http://opensource.teamdf.com/visible/examples/demo-basic.html
With the example above, you'd want to use detectPartial set to true -- so that you would know whether or not the thing is inside the viewport entirely.
//added by JG 3/10/2011, to extend selectors.
// Example:
//if ($('#whatever').is(':inView') ) {...}
jQuery.extend(jQuery.expr[':'], {
inView: function(a) {
var st = (document.documentElement.scrollTop || document.body.scrollTop),
ot = jQuery(a).offset().top,
wh = (window.innerHeight && window.innerHeight < jQuery(window).height()) ? window.innerHeight : jQuery(window).height();
return ot > st && (jQuery(a).height() + ot) < (st + wh);
}
});
I did that a number of years ago, based off of Remy Sharp's inview plugin (https://remysharp.com/2009/01/26/element-in-view-event-plugin) -- but these only check for vertical in-view, not horizontal (scrolling sideways/off the left or right).

How to get zoom working with turn.js

I am trying to make a flipbook using turn.js that has the same functionality as the example on the website http://www.turnjs.com/samples/magazine/
When looking at how to achieve this I came across these pages
http://www.turnjs.com/docs/Method:_zoom
http://turnjs.com/docs/How_to_add_zoom_to_turn.js
But after following these instructions on the pages my flipbook works nothing like the sample one.
I tried using the sample provided and breaking it down into sections to get mine working but I have not gotten any closer to solving this problem and the sample contains a bunch of other scripts and I am not sure if they are required for the zoom or are used for other things.
Not sure if I am missing something really simple or if my code is really off but my html looks something like this.
Right now all I get when clicking the zoom button is that the book scales up 150%
Was wondering if anyone could tell me what I am missing to get that zoom?
<div class="row">
<div id="zoom-viewport">
<div id="flipbook">
// wordpress loop
<div class="page">
// page contents
</div>
// end loop
</div>
</div>
</div>
and jQuery
//----------------------------
// Initialize
var _width = $('#flipbook-wrap').width(),
_height = Math.round(70.909090909/100*_width),
_winWidth = $window.width(),
_winHeight = $window.height();
$("#flipbook").turn({
width: _width,
height: _height,
autoCenter: true
});
//----------------------------
// Zoom in button
$('.fullscreen').click(function(e){
e.preventDefault();
$("#flipbook").turn("zoom", 1.5);
});

Your code isn't showing everything (e.g. where ".fullscreen" or the "zoom button" is in your HTML), so my answer may not be precise.
Looking at the sample, you should find the code:
$('.magazine-viewport').zoom('zoomIn', pos);
This seems to differ from turn('zoom', ...), and appears to be undocumented. This is a function that will zoom in the element defined as a turn object. I believe, for you, this is your "#flipbook" element, instead of ".magazine-viewport".
The parameters are "zoomIn" and pos, which may be a different functionality that what you're using currently. The "pos" appears to be a JS object that contains "x" and "y" properties, meant to define where you clicked on the magazine. These coordinates are relative to the magazine, not the whole screen, so keep that in mind.
So, I think you need something like this (at least try it at a starting point):
$('#flipbook').click(function(e) {
var pos = {
x: e.pageX - $(this).offset().left,
y: e.pageY - $(this).offset().top
};
$('#flipbook').zoom('zoomIn', pos);
});
Hope this helps!

To get zoom to work with turn.js, there are three things you need to do:
Setup the proper dom structure, zoom won't work without the "container" div to wrap the flipbook.
<div class="magazine-viewport">
<div class="container">
<div class='magazine'>
<div id='p1'><img src='book_1.jpg'></div>
<div id='p2'><img src='book_2.jpg'></div>
</div>
</div>
</div>
Setup the js events
$( document ).ready(function() {
//Initialize the turn.js flipbook
$('.magazine').turn({
width: 1136,
height:734,
pages:100,
autoCenter: false,
when:{
missing: function (e, pages) {
for (var i = 0; i < pages.length; i++) {
$('.magazine').turn('addPage',page[pages[i]],pages[i]);
}
}
}
});
//Initialize the zoom viewport
$('.magazine-viewport').zoom({
flipbook: $('.magazine')
});
//Binds the single tap event to the zoom function
$('.magazine-viewport').bind('zoom.tap', zoomTo);
//Optional, calls the resize function when the window changes, useful when viewing on tablet or mobile phones
$(window).resize(function() {
resizeViewport();
}).bind('orientationchange', function() {
resizeViewport();
});
//Must be called initially to setup the size
resizeViewport();
}
function page(num){
var elem = $('<div />',{}).html('<div><img src="book_'+num+'.jpg></div>');
return elem;
}
function zoomTo(event) {
setTimeout(function() {
if ($('.magazine-viewport').data().regionClicked) {
$('.magazine-viewport').data().regionClicked = false;
} else {
if ($('.magazine-viewport').zoom('value')==1) {
$('.magazine-viewport').zoom('zoomIn', event);
} else {
$('.magazine-viewport').zoom('zoomOut');
}
}
}, 1);
}
function resizeViewport() {
var width = $(window).width(),
height = $(window).height(),
options = $('.magazine').turn('options');
$('.magazine-viewport').css({
width: width,
height: height
}).zoom('resize');
}
Define proper css styles for the elements, the trick here is that the negative coordinates of the magazine class is compensated by the top & left offsets of the container class.
.magazine-viewport .container{
position:absolute;
top:367px;
left:568px;
width:1136px;
height:734px;
margin:auto;
}
.magazine-viewport .magazine{
width:1136px;
height:734px;
left:-568px;
top:-367px;
}
/* Important: the image size must be set to 100%.
* Otherwise the position of the images would be messed up upon zooming.
*/
.magazine img{
width:100%;
height:100%;
}
That should get it to work, if you want to load a larger version of the image upon zooming, take a look at the loadSmallPage() & loadLargePage() functions in the magazine example.

I had the same problem, but I decided to just use a third party zoom plugin (Jack Moore's jQuery zoom). It turns out the example in the site is a lot more complicated, with a json to create diferent regions and images for each paragraph.
It really depends on what you're using turn.js for, but I think the documentation isn't right, or the software itself is missing something. Either way, I do suggest you look into using some other solution for the problem.

turn.js provides an example with zoom. The difficulty to make it work is to gather all the required files. But if you watch the code, it is possible. Say the root is magazine, it goes two folders up to get lib and extras folders where java scripts are laying. In addition, you have to add the "default" and large pages in the pages folder. When you get the sample, there are only the thumbnails in. Say for 1-thumb.jpg, you have to add 1.jpg and 1-large.jpg
There is a very usefull Firefox plugin to get them : CacheViewer.
I have managed to do it with my book, and reorganize the paths in the code to have something cleaner: put lib and extras at the same level than pages. A recursive grep for "/../../" will give you all the locations in html and js code.

Custom parallax

I'm trying to create my own custom parallax plugin so that I am able to choose the direction the items transition off the screen and I'm just stuck at making sure that no matter how a user scrolls and no matter of the size of the window that the object disappears at the correct point.
Currently I have:
var lastScrollTop = 0;
var logoStartPos = $('.bg-logo').position().left;
$(function(){
$(window).scroll(function(){
var st = $(this).scrollTop();
if (st > lastScrollTop){
if($('.bg-logo').is(':in-viewport'))
$('.bg-logo').css({'left':($('.bg-logo').position().left+10) + "px"});
} else {
if($('.bg-logo').is(':in-viewport') && logoStartPos < $('.bg-logo').position().left)
$('.bg-logo').css({'left':($('.bg-logo').position().left-10) + "px"});
}
lastScrollTop = st;
});
});
As you can guess this only moves the item right until it goes off screen. This way has varied results because if I use the scroll wheel it take longer to disappear to if I use the scroll bar. I also have another problem in that if I use a mixture or have a different view port I get an different result all together.
Any tips or pointers to achieve the result I'm after?
An working example of my code is at http://motoring.egl.me.uk
Thanks Matt

A bit dated, but FYI...
In your jQuery initialize or ready event, you need to initialize each section, article, item or whatever it is (item.each) to instantiate a scroll function, so that each one has it's own scroll function.
this.each(function(index) {
Then in scroll function, only handle the event, if it is the 'current' section. You will need some way to determine which item is the 'current' one. Often this is done by saving each item's window size into a global array, and then using that compare to the current location.
Something like: (The way you designed your code will likely be very different)
// If this section is in view
if ( ($window.scrollTop() + $window.height()) > (topOffset) &&
( (topOffset + $self.height()) > $window.scrollTop() ) )
In this way, once one item goes off the screen, the next item should become 'current' and continue the scrolling.

Cloning content to a slider

I'm working on a responsive design, and would like some of my content in a slider when it's below a certain size. However, I would like to avoid rendering the data twice, so the idea is to clone the content and append it to the slider on (document).ready(), then initialise it. That way, I can show my content in the normal fashion in landscape mode, and in a slider in portrait mode (thus saving space).
var w = $(window).width();
if (w < 769) {
$("#container").children(".content").each(function () {
$(this).clone().appendTo("#slider ul").wrap("li");
});
initialiseSlider(); // Nothing special about this
}
The content is cloned to the slider container, but for some reason, it doesn't "slide". I'm thinking it may be because the slider is initialised before it has any content, because if I hardcode it, it works fine. Does that make sense? Any ideas on how I should fix this?

So actually, it might have been a whole different problem, possibly related to me having two of the same slider on the page.
var w = $(window).width();
if (w < 769) {
$('#programmeList').children('article').each(function () {
var data = $(this).clone().html();
$('#slider ul').append('<li>' + data + '</li>')
});
initialiseSlider();
}
Why they interfered, I don't know, as they had unique IDs and wasn't rendered at the same time anyway, but using append() instead of appendTo() helped.

Scroll to an element using jQuery

I need the page to scroll just so that an element is visible.
Options I've tried:
jQuery's scrollTo: the problem is that the page scrolls so that the element is on top (or at least it tries to do that, much like how this works: <a name="xyz"> / <a href="#xyz">). I want the minimum amount of scrolling, so that the entire element is visible (and, if the element is too tall, work like the anchor there).
scrollIntoView: awful. I want it to scroll smoothly (like $.scrollTo($('#id1'), 'fast');). Also, it doesn't seem to do what I want either.

What you need to do is identify the position within the page of the element, top and bottom (and left/right if you are considering horizontal scrolling). Then identify the current position of the viewport on the window, the scrollTop of the window should then be animated to whatever value will bring the other just in to view.
I just knocked up the following in this editor, so it's untested, but will give you the general idea for a plugin.
Updated - to show version that worked for the OP, as well as a smoother version
jQuery.fn.scrollMinimal = function(smooth) {
var cTop = this.offset().top;
var cHeight = this.outerHeight(true);
var windowTop = $(window).scrollTop();
var visibleHeight = $(window).height();
if (cTop < windowTop) {
if (smooth) {
$('body').animate({'scrollTop': cTop}, 'slow', 'swing');
} else {
$(window).scrollTop(cTop);
}
} else if (cTop + cHeight > windowTop + visibleHeight) {
if (smooth) {
$('body').animate({'scrollTop': cTop - visibleHeight + cHeight}, 'slow', 'swing');
} else {
$(window).scrollTop(cTop - visibleHeight + cHeight);
}
}
};
$('#item').scrollMinimal();

There's a plugin for just what you need
I don't want to copy the code from blog post, because it can get outdated (due to upgrades). But anyway. You can find all details and code about the .scrollintoview() jQuery plugin on blog post.
Usage
Contrary to scrollTo() plugin where you have to provide scrollable element this plugin only requires you to provide the element you'd like to scroll into view. Plugin finds nearest scrollable ancestor (with scrollbars) and scrolls to the element with animation, so user doesn't loose track of their position in the page.
The good thing is also that it won't scroll anything if element is already within visible boundaries of scrollable ancestor.
$("ElementSelector").scrollintoview();
That's it most of the time. But if you need to set some additional settings, there are some you can change and provide custom behaviour:
scrollintoview: function (options) {
/// <summary>Scrolls the first element in the set into view by scrolling its closest scrollable parent.</summary>
/// <param name="options" type="Object">Additional options that can configure scrolling:
/// duration (default: "fast") - jQuery animation speed (can be a duration string or number of milliseconds)
/// direction (default: "both") - select possible scrollings ("vertical" or "y", "horizontal" or "x", "both")
/// complete (default: none) - a function to call when scrolling completes (called in context of the DOM element being scrolled)
/// </param>
/// <return type="jQuery">Returns the same jQuery set that this function was run on.</return>

FYI, jQuery scrolling element into viewport plugins alternative:
intoViewPort plugin
scrollIntoView plugin