上传图片实时预览缩略图

< script language = JavaScript >
var  flag = false ;
function  DrawImage(ImgD) {
   var image=new Image();
   image.src=develop//develop/ImgD.src;
   if(image.width>0 && image.height>0){
    flag=true;
    if(image.width/image.height>= 120/80){
     if(image.width>120){  
     ImgD.width=120;
     ImgD.height=(image.height*120)/image.width;
     }else{
     ImgD.width=image.width;  
     ImgD.height=image.height;
     }
     ImgD.alt=image.width+"×"+image.height;
     }
    else{
     if(image.height>80){  
     ImgD.height=80;
     ImgD.width=(image.width*80)/image.height;     
     }else{
     ImgD.width=image.width;  
     ImgD.height=image.height;
     }
     ImgD.alt=image.width+"×"+image.height;
     }
    }
   /**//**//**//*else{
    ImgD.src="";
    ImgD.alt=""
    }*/
   }  

function  FileChange(Value) {
flag=false;
document.all.uploadimage.width=10;
document.all.uploadimage.height=10;
document.all.uploadimage.alt="";
document.all.uploadimage.src=/develop/Value;
}

function  BeforeUpLoad() {
if(flag) alert("OK");else alert("FAIL");
}
</ script >
< INPUT style = " WIDTH: 143px; HEIGHT: 18px "  type = file size = 8  name = pic onchange = " javascript:FileChange(this.value); " >  
< IMG id = uploadimage height = 10  width = 10  src = ""   onload = " javascript:DrawImage(this); "   >< BR >
< Button onclick = " javascript:BeforeUpLoad(); " > 提交 </ Button >

将以上代码保存为HTM文件，即可查看运行效果