IH-James
03-09-2004, 10:32 AM
Have you ever visited a web site where an image changed when you pointed your mouse over it?
Chances are, you probably have, but if not, I've created an example here (http://www.infernoforums.com/tutorials/jsMouseOvers/). The scource code for this example is attached to this tutorial (below).
This tutorial will show you how to achieve the effect seen in the example above.
Step 1
First of all, create your image that you wish to display when the page loads. Secondly, create the image that has the efffect(s) you wish to show when a visitor mouses over your initial image.
In the example above, I've called the first image home.gif, and the mouseover image home_over.gif. I suggest that you follow a similar naming convention.
Step 2
Add the following block of code to your existing web page somewhere between your opening head tag (<head>) and your closing head tag (</head>):
<script language="JavaScript" type="text/JavaScript">
<!--
function preloadImages() { //v3.0
var d=document; if(d.images){ if(!d.p) d.p=new Array();
var i,j=d.p.length,a=preloadImages.arguments; for(i=0; i<a.length; i++)
if (a[i].indexOf("#")!=0){ d.p[j]=new Image; d.p[j++].src=a[i];}}
}
function swapImgRestore() { //v3.0
var i,x,a=document.sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}
function findObj(n, d) { //v4.01
var p,i,x; if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=findObj(n,d.layers[i].document);
if(!x && d.getElementById) x=d.getElementById(n); return x;
}
function swapImage() { //v3.0
var i,j=0,x,a=swapImage.arguments; document.sr=new Array; for(i=0;i<(a.length-2);i+=3)
if ((x=findObj(a[i]))!=null){document.sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}
//-->
</script>
Step 3
Your existing image code should look something simlar to this:
<img src="images/home.gif" alt="Our Home Page" name="home" width="50" height="20" border="0" id="home">Note that the name & id attributes are set. You must set these to something that no other image on the page will have.
Add the following code to the left of the image code above:
<a href="homepage.html" onMouseOver="swapImage('home','','images/home_over.gif',1)" onMouseOut="swapImgRestore()">
You can change the href="" part to point to any page you wish, for example:
href="http://www.mydomain.com/homepage.html"
Now add the closing link code (below) to the right hand side of the image code above:
</a>
Step 4
At this stage the code would do what we require it to do, however it is better practice to preload the _over images when the page loads. This reduces the time delay between the visitor pointing the mouse over the image, and the _over image loading.
To do this, add this code to your <body> tag:
onLoad="preloadImages('images/home_over.gif')">
For example, if your body tag was <body>, it would now be:
<body onLoad="preloadImages('images/home_over.gif')">
Step 5
That's it!
Save your html file and view it in a web browser to see the results.
The complete source code is attached below:
Chances are, you probably have, but if not, I've created an example here (http://www.infernoforums.com/tutorials/jsMouseOvers/). The scource code for this example is attached to this tutorial (below).
This tutorial will show you how to achieve the effect seen in the example above.
Step 1
First of all, create your image that you wish to display when the page loads. Secondly, create the image that has the efffect(s) you wish to show when a visitor mouses over your initial image.
In the example above, I've called the first image home.gif, and the mouseover image home_over.gif. I suggest that you follow a similar naming convention.
Step 2
Add the following block of code to your existing web page somewhere between your opening head tag (<head>) and your closing head tag (</head>):
<script language="JavaScript" type="text/JavaScript">
<!--
function preloadImages() { //v3.0
var d=document; if(d.images){ if(!d.p) d.p=new Array();
var i,j=d.p.length,a=preloadImages.arguments; for(i=0; i<a.length; i++)
if (a[i].indexOf("#")!=0){ d.p[j]=new Image; d.p[j++].src=a[i];}}
}
function swapImgRestore() { //v3.0
var i,x,a=document.sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}
function findObj(n, d) { //v4.01
var p,i,x; if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=findObj(n,d.layers[i].document);
if(!x && d.getElementById) x=d.getElementById(n); return x;
}
function swapImage() { //v3.0
var i,j=0,x,a=swapImage.arguments; document.sr=new Array; for(i=0;i<(a.length-2);i+=3)
if ((x=findObj(a[i]))!=null){document.sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}
//-->
</script>
Step 3
Your existing image code should look something simlar to this:
<img src="images/home.gif" alt="Our Home Page" name="home" width="50" height="20" border="0" id="home">Note that the name & id attributes are set. You must set these to something that no other image on the page will have.
Add the following code to the left of the image code above:
<a href="homepage.html" onMouseOver="swapImage('home','','images/home_over.gif',1)" onMouseOut="swapImgRestore()">
You can change the href="" part to point to any page you wish, for example:
href="http://www.mydomain.com/homepage.html"
Now add the closing link code (below) to the right hand side of the image code above:
</a>
Step 4
At this stage the code would do what we require it to do, however it is better practice to preload the _over images when the page loads. This reduces the time delay between the visitor pointing the mouse over the image, and the _over image loading.
To do this, add this code to your <body> tag:
onLoad="preloadImages('images/home_over.gif')">
For example, if your body tag was <body>, it would now be:
<body onLoad="preloadImages('images/home_over.gif')">
Step 5
That's it!
Save your html file and view it in a web browser to see the results.
The complete source code is attached below: