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JavaScript rollover. Image swap

Windows : Internet Explorer 4.0+, Firefox 1.0+, Google Chrome, Opera 3.21+, Safari 3.1+, SeaMonkey 1.0+, [ 1 ].

Linux : Firefox 1.0+, Chromium, Opera 5.0+, SeaMonkey 1.0+, hv3, [ 2 ].

Example n.1 ( For modern web browsers: Internet Explorer 4.0+, Firefox 1.0+, Google Chrome, Opera 4.0+, Safari 3.1+, SeaMonkey 1.0+, [ 3 ] ):

JavaScript rollover. Image swap

HTML / XHTML. Code:

<a href="javascript-rollover-image-swap.htm" onmouseover="image_over();" onmouseout="image_out();"><img src="out.gif" class="image" id="imageout" width="728" height="67" alt="JavaScript rollover. Image swap" /></a>

CSS. Code:

.image {border: 0px;}

JavaScript. Code:

imageout=new Image();

imageout.src="out.gif";

imageover=new Image();

imageover.src="over.gif";

function image_out(){

document.images['imageout'].src='out.gif';

};

function image_over(){

document.images['imageout'].src='over.gif';

};

Swap image 1 ( out.gif ):

Swap image 2 ( over.gif ):

Example n.2 ( For older web browsers: Internet Explorer 4.0+, Netscape 3.04+, Opera 3.21+ ):

HTML / XHTML. Code:

<a href="javascript-rollover-image-swap.htm" onmouseover="image_over();" onmouseout="image_out();"><img src="out.gif" class="image" id="imageout" name="imageout" width="728" height="67" border="0" alt="JavaScript rollover. Image swap"></a>

JavaScript. Code:

imageout=new Image();

imageout.src="out.gif";

imageover=new Image();

imageover.src="over.gif";

function image_out(){

document.images['imageout'].src='out.gif';

};

function image_over(){

document.images['imageout'].src='over.gif';

};

Swap image 1 ( out.gif ):

Swap image 2 ( over.gif ):

Demo page 1 of Example n.2 - JavaScript code in external file - for Internet Explorer 4.0+, Netscape 3.04 - 4.xx, Opera 3.21 - 3.6x: [ Open demo page ] [ Download archive file ]

Demo page 2 of Example n.2 - JavaScript code inside the HTML document (it was used, for instance, for Netscape 3.xx displaying pages from web servers not configured to send the "application/x-javascript" MIME type for .js files) - for Internet Explorer 4.0+, Netscape 3.04 - 4.xx, Opera 3.21 - 3.6x: [ Open demo page ] [ Download archive file ]

JavaScript rollover. Image swap

There were fewer practical client side options in 1990s, than today to make a web page anything beyond simple. CSS was less developed, there were non-CSS web browsers still around even in about 1999. Internet connections were too often too slow. Java and JavaScript were the main way to visual effects on a web page. Java applets being in itself a very powerful tool are more complicated to learn and implement. So JavaScript was then more than now responsible for visual effects and less for technical part - handled more by server side technologies.

But later spread of web browsers with thorough CSS support, first .link, .visited, .hover, .active pseudo-classes, then background image positioning, @font-face and some others pushed JavaScript out of many visual effects areas. Also the Web has become more SEO aware in 2000s: this did a lot in favour of text over images and plug-ins content - which in its turn promoted the CSS case even more, taking some of JavaScript space even more as well. As for rollovers, JavaScript ones began to be often phased out in favour of CSS rollovers.

Now there are still cases when JavaScript rollovers are appropriate, but in other situations - like rollovers used in menus - CSS rollovers are more suitable. So JavaScript rollovers are in a way a living past still among us. Same as centering page content by table tag or table borders without CSS. Oldish, but still fully functional.

The concept :

1. Two images are loaded by a JavaScript code into web browser cache. And an image the same as one of the two preloaded is placed in the web document by img HTML tag.

2. When mouse pointer is moved over the image, the other preloaded one is displayed. When mouse pointer is moved out from the image, the initial one is displayed.

There are also other ways of creating rollovers, both the JavaScript ones and by other technologies: CSS, VBScript, Java, Flash, some others.


[ 1 ]

As well as Mozilla 0.6+ and Netscape 3.04+.

[ 2 ]

As well as Mozilla 0.6+ and Netscape 3.04+.

[ 3 ]

As well as Mozilla 0.6+ and Netscape 6.0+.


Aliosque subditos et thema

 

CSS vertical alignment

 

CSS vertical alignment of a block element containing text and images. It works for various combinations of inline and block elements. Example: CSS vertical alignment CSS vertical alignment HTML / XHTML. Code: <div class="parent"> <div class="child"> <div class="childcontent">CSS vertical alignment</div> <div class="childcontent"><img src="image.jpg" width="68" height="68" alt="Image" /></div> <div class="childcontent">CSS vertical alignment</div> </div> </div> CSS. Code: .parent {position: relative; left: 0px; top: 0px; height: 200px; display: table;} .child {position: relative; left: 0px; top: 0px; display: table-cell; vertical-align: middle;} .childcontent {position: relative; left: 0px; top: 0px;} Note: .parent and .childcontent may be floated left ("float: left;") or not, but .child must be without "float: left;" for this method of CSS vertical alignment to work. [ 1 ] As well as Netscape 6.01+, Mozilla 0.6+. [ 2 ] As well as Netscape 6.01+, Mozilla 0.6+.

CSS. Target Opera only

 

CSS targeting Opera web browser only: This text is red in Opera HTML / XHTML. Code: <p>This text is red in Opera</p> CSS. Code: doesnotexist:-o-prefocus, p {color: #f00;} The -o-prefocus pseudo-class allows styling elements for Opera browser only. The code is placed in the common CSS file, not in a separate one as it is in case of Internet Explorer conditional comments. Source: http://www.opera.com/docs/specs/presto2.12/css/o-vendor/ [ 1 ] Opera 3.5 - 5.0 ignores "doesnotexist:-o-prefocus" and reads code as p {color: #f00;}. Opera 6.0 - 9.4 ignores the whole code starting "doesnotexist". [ 2 ] Internet Explorer 5.5+, Firefox 1.0+, Google Chrome, Safari 3.1+, SeaMonkey 1.0+, Netscape 7.2+, Mozilla 1.5+ ignore the whole code starting "doesnotexist". Older browsers like Internet Explorer before 5.5 or Netscape before 7.2 or Mozilla before 1.5 seem to ignore the uncommon, Opera 9.5+ specific code ("doesnotexist:-o-prefocus") and apply styles to what they understand - here it is the p tag; making the text in it red. [ 3 ] The text is red in Dillo 3.0.1 as well.