Develop Reference

Prevent iframe from loading on mobile

I am working on my portfolio page and I want to have my projects in a demo mode where the user can preview the sites in different viewports. I got the idea from here:
http://my.studiopress.com/themes/genesis/#demo-full
On mobile devices I would like to keep the iframes from loading, and instead have links to the projects open the sites in the new tab.
If I have the divs containing the iframes hidden at the very top of my CSS file with display:none, I can see the iframes still load in the background and the page takes a long time to load.
Is there any way to keep them from loading at all when on a certain device or viewport size?

You could achieve this by using JavaScript and the HTML Data-Attribut. By setting the src-Attribute to something like "#" it won't load anything. You can use the data-Attribute to store the URL for use with JavaScript.
<iframe src="#" data-src="https://placekitten.com/200/300" frameborder="0"></iframe>
Then you just check to screen size with window.matchMedia() and set the src-attribute at a specific screen size.
var $iframe = $('iframe'),
src = $iframe.data('src');
if (window.matchMedia("(min-width: 480px)").matches) {
$iframe.attr('src', src);
}
Here is a working example: https://jsfiddle.net/5LnjL3uc/
If you want to show the iframe after a user resizes the window you need to put your code into a function and bind it to a resize event:
var $iframe = $('iframe'),
src = $iframe.data('src');
function showIframe() {
if (window.matchMedia("(min-width: 480px)").matches) {
$iframe.attr('src', src);
}
}
$(window).on('resize', showIframe);
// Initialize it once on document ready
showIframe();
Working Example: https://jsfiddle.net/5LnjL3uc/1/

A better solution is to approach this in reverse.
IE do not load the src to begin with by placing your URL in a attribute like 'data-src' for example.
See my code for this below. You simply copy the data-src to your src when your device, or device width is not mobile/mobile size.
I believe this is the best solution because there are no uncertainties. With the previously mentioned solutions (which I tried) you are racing against the clock with the browser for when your code runs and it decides to load the iframe src.
if(device !== true) {
// add '#' to the href
let iframe = document.getElementById('3dExperience')
iframe.src = iframe.getAttribute('data-src')
}
Note: 'device' is the is-mobile npm package for detecting mobile.

How to properly scroll IFrame to bottom in javascript

For a mockup-webpage used for research on interaction on websites, I created a mockup message-stream using JavaScript. This message stream is loaded in an IFrame and should show images at pre-set intervals and scroll to the bottom of the page after placing a new image at the bottom of the page. Getting the images to appear is working quite well with the provided script. However, both Chrome and IE seem to have trouble scrolling the page to the bottom. I would like to scroll to the bottom of the page as soon as the image is attached, but have for now added a 5 ms delay because that seemed to work sometimes. My questions are:
Is it okay to use document.body.scrollHeight for this purpose?
Can I make the scroll occur directly, or do I need a small interval before scrolling?
How to make the code scroll to the bottom of the IFrame directly after adding an image?
The following functions are used and trypost() is started onLoad:
function scrollToBottom(){
window.scrollBy(0,document.body.scrollHeight);
}
function trypost(){
point = point + 1;
if(point < interval.length){
//create and append a new image
var newImg = document.createElement("IMG");
newImg.src = "images/"+images[point]+".png";
document.getElementById('holder').appendChild(newImg);
//create and append a return
var br = document.createElement("br");
document.getElementById('holder').appendChild(br);
//time scroll to bottom (after an arbitrary 5 seconds)
var stb = window.setTimeout(scrollToBottom, 5);
//time next post
var nextupdate = interval[point]*400;
var tp = window.setTimeout(trypost, nextupdate);
}
}
My script section contains at least the following variables:
var point = -1;
var interval = [10, 10, 15];
var images = ["r1", "a1", "r2"];
This questions is a continuation of the project described in How to proper use setTimeout with IE?

To answer one of your questions, document.body.scrollHeight is appropriate for this purpose, but not if you're actually calling for document. That'll give you the scroll height of the document the iFrame is in, not the iFrame's document. The iFrame's document can be called upon by [insert variable for iFrame here].contentDocument.
Here's how I did it (and by that, I mean I tested it out with my own stuff to make sure it worked):
let i = document.querySelector('iframe')
i.contentWindow.scrollTo(0, i.contentDocument.body.scrollHeight);
That being said, the other answer by Thomas Urban will also work most of the time. The difference is only if your page has a really long scroll height. Most pages won't be longer than 999999 (for all I know that's impossible and that's why they chose that number), but if you have a page longer than that, the method I showed here would scroll to the bottom and the 999999 would scroll to somewhere not yet at the bottom.
Also note, if you have more than one iFrame, you're gonna want to query it in a different way than I did, like by ID.

Scrolling to bottom is always like scrolling to some ridiculously large top offset, e.g. 999999.
iframe.contentWindow.scrollTo( 0, 999999 );
In addition see this post: Scrolling an iframe with javascript?
If scrolling occurs too early it's probably due to images not being loaded yet. Thus, you will have to scroll as soon as added image has been loaded rather than on having placed it. Add
newImg.onload = function() { triggerScrolling(); };
after creating newImg, but before assigning property src.
If several events are required to trigger scrolling you might need to use some "event collector".
function getEventCollector( start, trigger ) {
return function() {
if ( --start == 0 ) { trigger(); )
};
}
You can then use it like this:
var collector = getEventCollector( 2, function() { triggerScrolling(); } );
newImg.onload = collector;
window.setTimeout( collector, 100 );
This way triggerScrolling() is invoked after 100ms at least and after image has been loaded for collector has to be invoked twice for triggerScrolling() being invoked eventually.

How to make an iframe auto-resize along with the dynamic changes on its content?

I have this js code I searched on auto-resizing iframe height with its content. It does what the user who posted this says it does. However, I now have this problem with dynamic content within the iframe.
The js code I have works only with the regular content of the page but not when there are dynamic changes going on within. For example, displaying texts through ajax call.
I've tried searching for other solutions to this but others did not work as well as what this code can do.
I'm hoping that there's someone who could help me update the code to meet what I currently need. I'm not very familiar with jquery/javascript to do this on my own. Thank you in advance! :)
This is the JS code:
function setIframeHeight(iframeId) {
var ifDoc, ifRef = document.getElementById(iframeId);
try {
ifDoc = ifRef.contentWindow.document.documentElement;
} catch (e) {
try {
ifDoc = ifRef.contentDocument.documentElement;
} catch (ee) {}
}
if (ifDoc) {
ifRef.height = 1;
ifRef.height = ifDoc.scrollHeight;
/* For width resize, enable below. */
//ifRef.width = 1;
//ifRef.width = ifDoc.scrollWidth;
}
}
I found this other code which enables iframe adapting to its dynamic content but I do not know how to make the code above and this work together. Please help me.
var iframe = document.getElementById("ifr").contentWindow;
iframe.$(".toggle_div").bind("change", function () {
$("#ifr").css({
height: iframe.$("body").outerHeight()
});
});
To summarize, I need a code that autoresizes iframe with its content and will autoresize again if there are changes on the size of the content.

The problem is that your page doesn't have any trigger indicating to resize when the iframe body resizes.
There also (as far as I know) isn't anything built into javascript that lets you watch for changes in an elements height.
You have two options.
If you are the owner of the iframe content, you can put a script in that page which can call to it's parent window telling the parent to run your resize script, or you can run a function which checks for changes say every second or so.
For the first method, you can follow the answer from here Can events fired from an iframe be handled by elements in its parent?
Otherwise just do a
setTimeout(function(){
$("#ifr").css({
height: iframe.$("body").outerHeight()
});
},1000);

function adjustMyFrameHeight()
{
var frame = getElement("myFrame");
var frameDoc = getIFrameDocument("myFrame");
frame.height = frameDoc.body.offsetHeight;
}
call this method on your iframe onload event and replace mtFrame to your iframe Id

Jquery.height() returns different results using F5 or CTRL+F5

So I am trying to find the height of my images then add a top margin this enables me to impose a a vertical center.
I'm running this code, and on an F5 refresh I get correct height but on CTRL+F5 refresh it gives me a much smaller height. I kind of assume this is a loading/delay thing, but I am using document ready so not really sure whats going on. I tried using a php function but it slows the site down amazingly so have to stick with jquery.
you can see it working here. www.mzillustration.com
jQuery(document).ready(function() {
if (jQuery('.imagedisplay').length != 0) {
jQuery('.imagedisplay').each(function(){
var imgheight = jQuery(this).find('img').height();
var topmarg = ((240 - imgheight) / 2) ;
jQuery(this).find('img').css({'margin-top':topmarg+'px'});
});
});
any ideas/help/explanation much appreciated.
thanks

There is a difference between onload and onready.
ready will wait until the actual DOM-tree is done, while onload will wait until ALL of the content displayed on the page is finnished loading. So an explanation would be that when clearing the cache and refreshing, the dom tree finishes much faster than the images, hence giving the wrong heigh.
Try using the onload-event instead and see if you get a different result.

You need to insure the image has loaded before asking the browser for its height. If that image path is living in the html you will unfortunately need a jquery pluggin to handle this in a cross browser manner.
https://github.com/alexanderdickson/waitForImages
http://desandro.github.com/imagesloaded/
Or you will have to wait for the window.onload event which in jquery looks like this:
$(window).on('load', function(){....
However if you use the window load event, it will wait until ALL resources have loaded and depending on your site that can be a serious delay when compared to measuring just the image itself.
Or if you are comfortable with loading the image from javascript, simply ordering your code properly will handle this:
var loadTester = new Image(),
imgH;
$(loadTest).on('load',function(){
imgH = $('#image').attr('src',loadTester.src).height();
}
loadTester.src = "paht/to/image.jpg";
The reason you are seeing a difference in the manner you reload the page, is that a simple refresh does not clear the cache, so the image is already loaded. When you hit ctrl+f5 it clears the cache and so the image is not yet loaded when you ask the browser for the height.
For cache control durring development consider getting the firefox web-developer toolbar.

Try this approach:
jQuery(function() {
jQuery('.imagedisplay img').each(function() {
var $this = jQuery(this),
height = $this.height();
if (height) {
$this.css('margin-top', ((240 - height) / 2) + 'px');
} else {
$this.on('load', function() {
$this.css('margin-top', ((240 - $this.height()) / 2) + 'px');
});
}
});
});

images are/can be cached/loaded separately from the actual page content. the document being ready can (and in my experience usually) occurs before everything is loaded.
try adding an event listener to the actual element being loaded.

You need to make sure the image has loaded before extracting a height. You can easily check this using the complete property on the image. Try this:
var setH = function() {
$(this).css('margin-top', (240 - this.height) / 2);
}
$('.imagedisplay img').each(function() {
if( this.complete ) {
setH.call(this); // apply height straight away
return;
}
$(this).load(setH); // apply height when the image has loaded
});

Computing a cross-browser iframe height

One of the most difficult problems in my javascript experience has been the correct (that is "cross-browser") computing of a iframe height.
In my applications I have a lot of dynamically generated iframe and I want them all do a sort of autoresize at the end of the load event to adjust their height and width.
In the case of height computing my best solution is the following (with the help of jQuery):
function getDocumentHeight(doc) {
var mdoc = doc || document;
if (mdoc.compatMode=='CSS1Compat') {
return mdoc.body.offsetHeight;
}
else {
if ($.browser.msie)
return mdoc.body.scrollHeight;
else
return Math.max($(mdoc).height(), $(mdoc.body).height());
}
}
I searched the internet without success. I also tested Yahoo library that has some methods for document and viewport dimensions, but it's not satisfactory.
My solution works decently, but sometimes it calculates a taller height.
I've studied and tested tons of properties regarding document height in Firefox/IE/Safari: documentElement.clientHeight, documentElement.offsetHeight, documentElement.scrollHeight, body.offsetHeight, body.scrollHeight, ...
Also jQuery doesn't have a coherent behavior in various browser with the calls $(document.body).height(), $('html', doc).height(), $(window).height()
I call the above function not only at the end of load event, but also in the case of dynamically inserted DOM elements or elements hidden or shown. This is a case that sometimes breaks the code that works only in the load event.
Does someone have a real cross-browser (at least Firefox/IE/Safari) solution? Some tips or hints?

Although I like your solution, I've always found IFRAMEs to be more trouble than they're worth.
Why ? 1. The sizing issue. 2. the iframe has that src attribute to worry about. i.e. absolute path. 3. the extra complexity with the pages.
My solution - DIVs which are dynamically loaded through AJAX calls. DIVs will auto size. Although the AJAX code requires javascript work (which can be done through frameworks) they are relative to where the site is. 3 is a wash, you're trading complexity in pages up to javascript.
Instead of <IFRAME ...> use <DIV id="mystuff" />
Do the ajax call to fill the mystuff div with data and let the browser worry about it.

This has been without an accepted answer for awhile, so I wanted to contribute the solution I ended up going with after some research. This is cross-browser and cross-domain (e.g. when the iframe points to content from a different domain)
I ended up using html5's message passing mechanism wrapped in a jQuery pluging that makes it compatible with older browsers using various methods (some of them described in this thread).
The end solution is very simple.
On the host (parent) page:
// executes when a message is received from the iframe, to adjust
// the iframe's height
$.receiveMessage(
function( event ){
$( 'my_iframe' ).css({
height: event.data
});
});
// Please note this function could also verify event.origin and other security-related checks.
On the iframe page:
$(function(){
// Sends a message to the parent window to tell it the height of the
// iframe's body
var target = parent.postMessage ? parent : (parent.document.postMessage ? parent.document : undefined);
$.postMessage(
$('body').outerHeight( true ) + 'px',
'*',
target
);
});
I've tested this on Chrome 13+, Firefox 3.6+, IE7, 8 and 9 on XP and W7, safari on OSX and W7. ;)

Since in your example you're accessing the document inside the IFRAME I guess you're talking about knowing the height of the document and not of the frame itself. Also, that means that the content comes from your own website and you have control over it's contents.
So, why don't you simply place a DIV around your content and then use the clientHeight of that DIV?
Code you load in your IFRAME:
...
<body>
<div id="content">
...
</div>
</body>
The parent document:
function getDocumentHeight(mdoc) {
return mdoc.getElementById("content").clientHeight;
}
BTW, this part of your example function does not make sense as "document" does not refer to the IFRAME:
var mdoc = doc || document;

Here is a solution that seems to work. Basically, the scrollHeight is the correct value in most cases. However, in IE (specifically 6 and 7), if the content is simply contained in text nodes, the height is not calculated and just defaults to the height set in CSS or on the "height" attribute on the iframe. This was found through trial and error, so take it for what it is worth.
function getDocumentHeight(doc) {
var mdoc = doc || document;
var docHeight = mdoc.body.scrollHeight;
if ($.browser.msie) {
// IE 6/7 don't report body height correctly.
// Instead, insert a temporary div containing the contents.
var child = $("<div>" + mdoc.body.innerHTML + "</div>", mdoc);
$("body", mdoc).prepend(child);
docHeight = child.height();
child.remove();
}
return docHeight;
}

I have found this solution to work in ie 6+, ff 3.5+, safari 4+. I am creating and appending an iframe to the document. The following code is executed at the end of jQuery's load event after some other dom manipulation. The timeout is needed for me because of the additional dom manipulation taking place in the load event.
// sizing - slight delay for good scrollheight
setTimeout(function() {
var intContentHeight = objContentDoc.body.scrollHeight;
var $wrap = $("#divContentWrapper", objContentFrameDoc);
var intMaxHeight = getMaxLayeredContentHeight($wrap);
$this.height(intContentHeight > intMaxHeight ? intMaxHeight : intContentHeight);
// animate
fireLayeredContentAnimation($wrap);
}, 100);
I have some sizing constraints to consider, which is what the getMaxLayeredContentHeight call is checking for me. Hope that helps.

Here's a script that resizes the iFrame depending on the body inside it's height.