Develop Reference

Why the image is broken occasionally with the hover

$(function () {
$(".btn").on("mouseover",function(){
$(this).attr("src", $(this).attr("src").replace("images", "images/hover"));
});
$(".btn").on("mouseleave",function(){
$(this).attr("src", $(this).attr("src").replace("images/hover", "images"));
});
});
The above code is the way I change the image when the user hover on the button, when user click on it , it will redirect to other page. And the Html element is like:
<img class="btn" src="images/index_03.gif" />
The problem is , I am sure the path is correct , but when the user click on the button , during the time of loading the next page or in some case, when i hover on the image , the hovered image is not shown but broken link, why is it and how to fix it? Thanks for helping

$(this).attr("src", $(this).attr("src").replace("images/hover", "images"));
This code will reload the image, every time (or from cache).
So, during the page loading as other data is also loading at the same time, onhover image loading will be slow or broken.
I suggest you should load both images at the same time and at the same position and show/hide them on hover to get faster results.

Using CSS sprites instead of javascript calls will eliminate mouseover flickering, and reduce the total number of http requests required for your site (making it load faster).
You can achieve the same 'mouseover' functionality by using the css ':hover' pseudo element to alter the 'clip' property of the image (supported in IE6 and above).
Check out these CSS Tricks articles:
CSS Sprites: What They Are, Why They’re Cool, and How To Use Them.
CSS Sprites with Inline Images

Html5 image Pixelation load

In my website, images are loaded from top to bottom, how can I change it so the images will load in Pixelation, like on Google Maps when are you zooming in?

Or if you want a pixelating/rendering blur, you could look here: https://www.google.com/amp/s/jmperezperez.com/medium-image-progressive-loading-placeholder/amp/
Here is what is going on:
Render a div where the image will be displayed. Medium uses a with a padding-bottom set to a percentage, which corresponds to the aspect ratio of the image. Thus, they prevent reflows while the images are loaded since everything is rendered in its final position. This has also been referred to as intrinsic placeholders.
Load a tiny version of the image. At the moment, they seem to be requesting small JPEG thumbnails with a very low quality (e.g. 20%). The markup for this small image is returned in the initial HTML as an , so the browser starts fetching them right away.
Once the image is loaded, it is drawn in a . Then, the image data is taken and passed through a custom blur() function You can see it, a bit scrambled, in the main-base.bundle JS file. This function is similar, though not identical, to StackBlur‘s blur function. At the same time, the main image is requested.
Once the main image is loaded, it is shown and the canvas is hidden.
All the transitions are quite smooth, thanks to the CSS animations applied.
An example fromo the page:
<figure name="7012" id="7012" class="graf--figure graf--layoutFillWidth graf-after--h4">
<div class="aspectRatioPlaceholder is-locked">
<div class="aspect-ratio-fill" style="padding-bottom: 66.7%;"></div>
<div class="progressiveMedia js-progressiveMedia graf-image is-canvasLoaded is-imageLoaded" data-image-id="1*sg-uLNm73whmdOgKlrQdZA.jpeg" data-width="2000" data-height="1333" data-scroll="native">
<img src="https://cdn-images-1.medium.com/freeze/max/27/1*sg-uLNm73whmdOgKlrQdZA.jpeg?q=20" crossorigin="anonymous" class="progressiveMedia-thumbnail js-progressiveMedia-thumbnail">
<canvas class="progressiveMedia-canvas js-progressiveMedia-canvas" width="75" height="47"></canvas>
<img class="progressiveMedia-image js-progressiveMedia-image __web-inspector-hide-shortcut__" data-src="https://cdn-images-1.medium.com/max/1800/1*sg-uLNm73whmdOgKlrQdZA.jpeg" src="https://cdn-images-1.medium.com/max/1800/1*sg-uLNm73whmdOgKlrQdZA.jpeg">
<noscript class="js-progressiveMedia-inner"><img class="progressiveMedia-noscript js-progressiveMedia-inner" src="https://cdn-images-1.medium.com/max/1800/1*sg-uLNm73whmdOgKlrQdZA.jpeg"></noscript>
</div>
</div>
</figure>
Or you could check out this CodePen That JMPerez set up, in an atempt to recreate the effect himself.
I'm sorry about my first answer if its not what you were looking for.

jQuery delay until background image is loaded, then faded in?

I've been doing alot of research and there are loads of plugins and tutorials out there that cover the use of large background images. Unfortunately, they all have one thing in common - they use absolutely positioned images to behave as "fake" background images.
Normally that would work fine for me and I've done that before, however, this project has a repeating background image, so it's necessary that I use normal CSS rules to declare the background image.
All of that being said, is there a way to check to see if the image is loaded and tell jQuery to fade this background image in once it is loaded? The main thing I'm looking for is a way for jQuery to verify that the image is actually loaded. If not, then I suppose I need to settle for a simple static delay (which unfortunately ruins the effect for users who have slow connections).
Last thing - can this be done via CSS class switching/toggling so that I can change the body class before and after the image is loaded? This would be a fallback for users without javascript and would make it so I don't have to .hide() my entire body while the background image loads.
*EDIT: This thread seems to have a similar discussion but I don't think it's quite the same thing: How do I delay html text from appearing until background image sprite is loaded? *
* EDIT 2 *
Looks like the above thread worked after all, except I'm still missing the fadeIn effect. I set the fadeIn intentionally high and it's not animating for some reason, any ideas why?
<script>
$(function() {
// create a dummy image
var img = new Image();
// give it a single load handler
$(img).one('load',function() {
$('html').css('background','url(<?php bloginfo( 'template_url' ); ?>/images/red_curtain.jpg) top center repeat-y').fadeIn(12000); // fade in the elements when the image loads
});
// declare background image source
img.src = "<?php bloginfo( 'template_url' ); ?>/images/red_curtain.jpg";
// make sure if fires in case it was cached
if( img.complete )
$(img).load();
});
</script>

This seems an old thread but I found a solution for this.
Hope it can help:
$(window).load(function(){
$('<img/>').attr('src', 'images/imgsrc.png').load(function() {
$('#loading').fadeOut(500);
$('#wrapper').fadeIn(200);
});
});

Use $(document).load() to achieve what you want.
"I set the fadeIn intentionally high and it's not animating for some reason, any ideas why?"
It is, just before the page has loaded

Add display: none; to your body tag
<body style="display: none">
Then with jQuery modify your code so it looks like this:
$(img).load(function(){
$("body").show();
});
Now page content will only show after img loading is complete.

To check when the image is loaded, declare another, "regular" image (i.e. the <img> tag) with the same src and attach event handler to it. Browser won't load the same image twice, so that event will also mean that the background is loaded.
Another trick I can propose is to go back to "fake" background. In order to make it "tile", you can create an iframe, stretched to cover the whole body, and having that image as background, and then fade that iframe as you like, while the rest of the page remains safely in the "main" frame.

How to keep div focus when the mouse enters a child node

So I have this page here:
http://www.eminentmedia.com/development/powercity/
As you can see when you mouse over the images the div slides up and down to show more information. Unfortunately I have 2 problems that i can't figure out and I've searched but haven't found quite the right answer through google and was hoping someone could point me in the direction of a tutorial.
The first problem is that when you mouse over an image it changes to color (loads a new image), but there's a short delay when the image is loading for the first time so the user sees white. Do I have to preload the images or something in order to fix that?
My second problem is that when you move your mouse over the 'additional content area' it goes crazy and starts going up and down a bunch of times. I just don't have any idea what would cause this but i hope one of you will!
All my code is directly in the source of that page if you would like to view the source.
Thanks in advance for your help!

Yes, you have to preload the images. Thankfully, this is simple:
var images_to_preload = ['myimage.jpg', 'myimage2.jpg', ...];
$.each(images_to_preload, function(i) {
$('<img/>').attr({src: images_to_preload[i]});
});
The other thing you have to understand is that when you use jQuery you have to truly embrace it or you will end up doing things the wrong way. For example, as soon as you find yourself repeating the same piece of code in different places, you are probably doing something wrong. Right now you have this all over the place:
<div id="service" onmouseover="javascript:mouseEnter(this.id);" onmouseout="javascript:mouseLeave(this.id);">
Get that out of your head. Now. Forever. Always. Inline javascript events are not proper, especially when you have a library like jQuery at your disposal. The proper way to do what you want is this:
$(function() {
$('div.box').hover(function() {
$(this).addClass('active');
$(this).find('div.slideup').slideDown('slow');
}, function() {
$(this).removeClass('active');
$(this).find('div.slideup').slideUp('slow');
});
});
(You have to give all the #industrial, #sustainable, etc elements a class of 'box' for the above to work)
These changes will also fix your sliding problem.

I can see your images (the ones that are changing) are set in the background of a div. Here is a jquery script that preloads every image found in a css file. I have had the same problem in the past and this script solves it. It is also very easy to use:
http://www.filamentgroup.com/lab/update_automatically_preload_images_from_css_with_jquery/
I will take a look at your other problem...

1) You should be using the jquery events to drive your mouseovers. Give each div a class to indicate that its a category container and use the hover function to produce the mouseover/mouseout action you're after.
html
<div id="industrial" class="category"></div>
Javascript
$(".category").hover(
function () {
$(this).find('.container').show();
},
function () {
$(this).find('.container').hide();
}
);
I simplified the code to just do show and hide, you'll need to use your additional code to slide up and slide down.
2) Yes, you need to preload your images. Another option would be "sprite" the images. This would involve combining both the black and white and colour versions of each image into a single image. You then set it as the div's background image and simply use CSS to adjust the background-position offset. Essentially, sliding instantly from the black and white to colour images as you rollover. This technique guarentees that both images are fully loaded.

How does Bing.com create enlarged thumbnails?

When I search images using Bing.com, I realize their images are well cropped and sorted. When you place your mouse on an image, another window will pop up with an enlarged image.
http://www.bing.com/images/search?q=Heros&FORM=BIFD#
I want to do the same thing in my program. I checked the source code of their page. They are using javascript, but still I have no clue how they make it. Does anyone familiar with it? Any suggestion is welcomed.

If you look at the HTML, you'll see a span immediately above each of the images. It sets that frame's display style from "none" to "block". It then uses an animation library to resize the content of the covering frame.

It's the same image. It just enlarges it slightly.

Here's a simple HTML/CSS/Javascript example on changing the display property of an element with javascript:
HTML:
<div id="image1" class="image" onmouseover="showImg(1);">
Here's the small image
</div>
<div id="bigImage1" class="bigImage" onmouseout"hideImg(1);">
Here's the enlarged image and info about the picture
</div>
Javascript:
function showImg(num){
document.getElementById('bigImage' + num).style.display='block';
}
function hideImg(num){
document.getElementById('bigImage' + num).style.display='none';
}
CSS:
.bigImage{
display:none
}
They also use a fancy transition thing like scriptaculous's effect-grow found here.