JavaScript Forum

**ehentai** · 07-21-2007, 02:16 PM

My website has an header. A field of the header has an image. What I'm trying to do is that the image displayed there varies. That is, the image there would rotate (or maybe be random) from a serie of other images (all the images would have the same size).

I know there's a lot of stuff like this already done. Can someone give me a link to a script that does this (but that's easy to understand and, most of all, is very fast to load).

Thanks.

**Guerrilla** · 07-22-2007, 04:06 PM

http://www.google.co.uk/search?hl=en...e+Search&meta=

**tripy** · 07-22-2007, 04:29 PM

HTML Code:

<html>
  <head>
    <title>testing...</title>
  </head>
  <body>
    <script type="text/javascript">
    var aryImg=new Array("/img/img1.jpg", "/img/img2.jpg", "/img/img3.jpg");
    var rdm=Math.floor(Math.random()*aryImg.length)
    document.write('<img src="'+aryImg[rdm]+'" border="0" width="100" height="100" alt="'+aryImg[rdm]+'"/>');
    </script>
  </body>
</html>

Adapt aryImg with the images you want to randomize, and the img tag outputted options, and you should be ok

**ehentai** · 07:43 AM

Many thanks, I thought it would be something like that...

Just a question, if someone is seeing the webpage with Javascript disabled (like the Adblock add-on for Firefox), nothing will appear in the place a random picture should be, right?

Is there a way to make a default image appear to those without Javascript enabled?
If possible, I would like that picture to be loaded only by them (so that a person that has Javascript enabled won't need to load two pictuires).

Thanks

**tripy** · 07-24-2007, 08:09 AM

Simply add a <noscript> after the script tag.

HTML Code:

<html>
  <head>
    <title>testing...</title>
  </head>
  <body>
    <script type="text/javascript">
    var aryImg=new Array("/img/img1.jpg", "/img/img2.jpg", "/img/img3.jpg");
    var rdm=Math.floor(Math.random()*aryImg.length)
    document.write('<img src="'+aryImg[rdm]+'" border="0" width="100" height="100" alt="'+aryImg[rdm]+'"/>');
    </script>
    <noscript>
      <img src="/img/default.jpg" border="0" width="100" height="100" alt="default"/>
    </noscript>
  </body>
</html>

**ehentai** · 07-24-2007, 10:17 AM

Quote:

Originally Posted by tripy

Simply add a <noscript> after the script tag.

...But what's inside the <noscript> tag will be loadd even if someone can see Javascript, am I wrong?
Or if someone can see Javascript, what's inside the <noscript> won't be launched?

Thanks.

**tripy** · 07-24-2007, 10:32 AM

No, the noscript is interpreted only when a browser have no javascript support or the javascript is disabled

**ehentai** · 07-25-2007, 05:14 AM

Quote:

Originally Posted by tripy

No, the noscript is interpreted only when a browser have no javascript support or the javascript is disabled

Wow, that's really clever

Another question: I know a bit of Java and compilers but nothing of Javascript...
I mean, I intend to make the array of images with around 40 of them. But the browser will always have to build the array first, right? Into memory... so that means that the bigger the array, the longer it will take to complete the execution of the script, am I right?

**tripy** · 07-25-2007, 05:28 AM

Yep, that's right.
But don't worry for a 40 cells vector, that won't take that long to be loaded.

Javascript being a scripted language, it's a necessary phase.
Beside, just for the records, javascript have nothing related to java.
It's just the name that Netscape team decided to give it at the time where Java was really the "hot thing" to grab more attention to the product.
http://en.wikipedia.org/wiki/Javascr...ory_and_naming

Quote:

JavaScript was originally developed by Brendan Eich of Netscape under the name Mocha, later LiveScript, and finally renamed to JavaScript. The change of name from LiveScript to JavaScript roughly coincided with Netscape adding support for Java technology in its Netscape Navigator web browser. JavaScript was first introduced and deployed in the Netscape browser version 2.0B3 in December of 1995. The naming has caused confusion, giving the impression that the language is a spinoff of Java, which is not the case; and has been characterized by many as a marketing ploy by Netscape to give JavaScript the cachet of what was then the hot new web-programming language. [1] [2]

They have realised something there is close for the syntaxic part, but that's all.