I'm using a script on the homepage of a website for a photographer which displays an image selected at random from an array. I have found two different scripts which perform this function. I'd like to know which script is preferable and if it has been written correctly or can be improved. I wonder if it is possible to include a function that would prevent the same image from loading twice until all of the images in the array have been used. Thanks for taking a look.
Version 1
<script type="text/javascript">
<!--
var theImages = new Array()
theImages[1] = 'portrait/fpo/01.jpg'
theImages[2] = 'portrait/fpo/02.jpg'
theImages[3] = 'portrait/fpo/03.jpg'
theImages[4] = 'portrait/fpo/04.jpg'
theImages[5] = 'portrait/fpo/05.jpg'
theImages[6] = 'portrait/fpo/06.jpg'
theImages[7] = 'portrait/fpo/07.jpg'
theImages[8] = 'portrait/fpo/08.jpg'
theImages[9] = 'portrait/fpo/09.jpg'
theImages[10] = 'portrait/fpo/10.jpg'
var j = 0
var p = theImages.length;
var preBuffer = new Array()
for (i = 0; i < p; i++){
preBuffer[i] = new Image()
preBuffer[i].src = theImages[i]
}
var whichImage = Math.round(Math.random()*(p-1));
function showImage(){
document.write('<img src="images/'+theImages[whichImage]+'">');
}
// -->
</script>
<table cellpadding="0" cellspacing="0" border="0" height="100%" width="100%">
<tr valign="middle"><td align="center">
<a href="index.html"><script type="text/javascript">showImage();</script></a>
</td></tr>
</table>
Version 2
<script type="text/javascript">
<!--
var ic = 11; // Number of alternative images
var xoxo = new Array(ic); // Array to hold filenames
xoxo[0] = "images/portrait/fpo/01.jpg"
xoxo[1] = "images/portrait/fpo/02.jpg"
xoxo[2] = "images/portrait/fpo/03.jpg"
xoxo[3] = "images/portrait/fpo/04.jpg"
xoxo[4] = "images/portrait/fpo/05.jpg"
xoxo[5] = "images/portrait/fpo/06.jpg"
xoxo[6] = "images/portrait/fpo/07.jpg"
xoxo[7] = "images/portrait/fpo/08.jpg"
xoxo[8] = "images/portrait/fpo/09.jpg"
xoxo[9] = "images/portrait/fpo/10.jpg"
xoxo[10] = "images/portrait/fpo/11.jpg"
function pickRandom(range) {
if (Math.random)
return Math.round(Math.random() * (range-1));
else {
var now = new Date();
return (now.getTime() / 1000) % range;
}
}
// Write out an IMG tag, using a randomly-chosen image name.
var choice = pickRandom(ic);
// -->
</script>
<table cellpadding="0" cellspacing="0" border="0" height="100%" width="100%">
<tr valign="middle"><td align="center">
<a href="index-alternate.html"><script type="text/javascript">document.writeln('<img src="'+xoxo[choice]+'" >');</script></a>
</td></tr>
</table>
I'm using a script on the homepage of a website for a photographer which displays an image selected at random from an array. I have found two different scripts which perform this function. I'd like to know which script is preferable and if it has been written correctly or can be improved. I wonder if it is possible to include a function that would prevent the same image from loading twice until all of the images in the array have been used. Thanks for taking a look.
Version 1
<script type="text/javascript">
<!--
var theImages = new Array()
theImages[1] = 'portrait/fpo/01.jpg'
theImages[2] = 'portrait/fpo/02.jpg'
theImages[3] = 'portrait/fpo/03.jpg'
theImages[4] = 'portrait/fpo/04.jpg'
theImages[5] = 'portrait/fpo/05.jpg'
theImages[6] = 'portrait/fpo/06.jpg'
theImages[7] = 'portrait/fpo/07.jpg'
theImages[8] = 'portrait/fpo/08.jpg'
theImages[9] = 'portrait/fpo/09.jpg'
theImages[10] = 'portrait/fpo/10.jpg'
var j = 0
var p = theImages.length;
var preBuffer = new Array()
for (i = 0; i < p; i++){
preBuffer[i] = new Image()
preBuffer[i].src = theImages[i]
}
var whichImage = Math.round(Math.random()*(p-1));
function showImage(){
document.write('<img src="images/'+theImages[whichImage]+'">');
}
// -->
</script>
<table cellpadding="0" cellspacing="0" border="0" height="100%" width="100%">
<tr valign="middle"><td align="center">
<a href="index.html"><script type="text/javascript">showImage();</script></a>
</td></tr>
</table>
Version 2
<script type="text/javascript">
<!--
var ic = 11; // Number of alternative images
var xoxo = new Array(ic); // Array to hold filenames
xoxo[0] = "images/portrait/fpo/01.jpg"
xoxo[1] = "images/portrait/fpo/02.jpg"
xoxo[2] = "images/portrait/fpo/03.jpg"
xoxo[3] = "images/portrait/fpo/04.jpg"
xoxo[4] = "images/portrait/fpo/05.jpg"
xoxo[5] = "images/portrait/fpo/06.jpg"
xoxo[6] = "images/portrait/fpo/07.jpg"
xoxo[7] = "images/portrait/fpo/08.jpg"
xoxo[8] = "images/portrait/fpo/09.jpg"
xoxo[9] = "images/portrait/fpo/10.jpg"
xoxo[10] = "images/portrait/fpo/11.jpg"
function pickRandom(range) {
if (Math.random)
return Math.round(Math.random() * (range-1));
else {
var now = new Date();
return (now.getTime() / 1000) % range;
}
}
// Write out an IMG tag, using a randomly-chosen image name.
var choice = pickRandom(ic);
// -->
</script>
<table cellpadding="0" cellspacing="0" border="0" height="100%" width="100%">
<tr valign="middle"><td align="center">
<a href="index-alternate.html"><script type="text/javascript">document.writeln('<img src="'+xoxo[choice]+'" >');</script></a>
</td></tr>
</table>
- You're missing one of your pictures in the first version, fyi. I would go with 2. 1 is loading all of the images up front (more useful if you'll be changing images while the page is loaded). So it uses more bandwidth and will make your page load slower. – John Hoven Commented Apr 27, 2011 at 19:13
2 Answers
Reset to default 3This code will load images randomly and his respective link to load.
<html>
<head/>
<title>Jorgesys Android</title>
<script type="text/javascript">
var imageUrls = [
"http://stacktoheap./images/stackoverflow.png"
, "http://stacktoheap./images/stackoverflow.png"
, "http://stacktoheap./images/stackoverflow.png"
, "http://stacktoheap./images/stackoverflow.png"
, "http://stacktoheap./images/stackoverflow.png"
, "http://stacktoheap./images/stackoverflow.png"
];
var imageLinks = [
"http://www.stackoverflow."
, "http://www.reforma."
, "http://www.nytimes./"
, "http://www.elnorte./"
, "http://www.lefigaro.fr/international/"
, "http://www.spiegel.de/international/"
];
function getImageHtmlCode() {
var dataIndex = Math.floor(Math.random() * imageUrls.length);
var img = '<a href=\"' + imageLinks[dataIndex] + '"><img src="';
img += imageUrls[dataIndex];
img += '\" alt=\"Jorgesys Android\"/></a>';
return img;
}
</script>
</head>
<body bgcolor="black">
<script type="text/javascript">
document.write(getImageHtmlCode());
</script>
</body>
</html>
Decided to make it an answer.
FYI... You're missing one of your pictures in the first version, fyi.
I would go with 2. 1 is loading all of the images up front (more useful if you'll be changing images, doing a slide-show type thing). So it uses more bandwidth and will make your page load slower.
2 looks fine but I might change pickRandom(ic) to pickRandom(xoxo.length) so you don't have to forget about updating ic as you add more images.
You would probably want either to create a cookie for the user (lastImageIndex) to loop through the items. If cookies aren't available, just use a random image. Otherwise, start at a random image. Then each time accessed with the cookie increment. When you reach the length, go back to 0.
function getCookieValue(choice){
// read cookie here, if found, parseInt(cookieValue,10) and assign to choice
// Then return choice (either original value or updated)
return choice;
}
var choice = pickRandom(xoxo.length);
choice = getCookieValue(choice);
// Check if it correspond to an image
if (choice >= xoxo.length) choice = 0;
// Store the cookie here. Store choice++
That description is slightly different than what you asked for, since its per user, but I'd bet it gives you more the result you are looking for.