在上传图片前，提供预览功能(Javascript)
1. Copy the coding into the HEAD of your HTML document
2. Add the last code into the BODY of your HTML document -->
<!-- STEP ONE: Paste this code into the HEAD of your HTML document -->
<HEAD>
<script type="text/javascript">
<!-- Begin
/* This script and many more are available free online at
The JavaScript Source!! http://javascript.internet.com
Created by: Abraham Joffe :: http://www.abrahamjoffe.com.au/ */
/***** CUSTOMIZE THESE VARIABLES *****/
// width to resize large images to
var maxWidth=100;
// height to resize large images to
var maxHeight=100;
// valid file types
var fileTypes=["bmp","gif","png","jpg","jpeg"];
// the id of the preview image tag
var outImage="previewField";
// what to display when the image is not valid
var defaultPic="spacer.gif";
/***** DO NOT EDIT BELOW *****/
function preview(what){
var source=what.value;
var ext=source.substring(source.lastIndexOf(".")+1,source.length).toLowerCase();
for (var i=0; i<fileTypes.length; i++) if (fileTypes[i]==ext) break;
globalPic=new Image();
if (i<fileTypes.length) globalPic.src=source;
else {
globalPic.src=defaultPic;
alert("THAT IS NOT A VALID IMAGE\nPlease load an image with an extention of one of the following:\n\n"+fileTypes.join(", "));
}
setTimeout("applyChanges()",200);
}
var globalPic;
function applyChanges(){
var field=document.getElementById(outImage);
var x=parseInt(globalPic.width);
var y=parseInt(globalPic.height);
if (x>maxWidth) {
y*=maxWidth/x;
x=maxWidth;
}
if (y>maxHeight) {
x*=maxHeight/y;
y=maxHeight;
}
field.style.display=(x<1 || y<1)?"none":"";
field.src=globalPic.src;
field.width=x;
field.height=y;
}
// End -->
</script>
</HEAD>
<!-- STEP TWO: Copy this code into the BODY of your HTML document -->
<BODY>
<div align="center" style="line-height: 1.9em;">
Test it by locating a valid file on your hard drive:
<br>
<input type="file" id="picField" onchange="preview(this)">
<br>
<img alt="Graphic will preview here" id="previewField" src="spacer.gif">
<br> <div style="font-size: 7pt;">
Script submitted by: <a href="http://www.abrahamjoffe.com.au/">Sydney Wedding Video / DVD</a></div>
</div>
<p><center>
<font face="arial, helvetica" size"-2">Free JavaScripts provided<br>
by <a href="http://javascriptsource.com">The JavaScript Source</a></font>
</center><p>
