JS 客户端验证文件类型，获取图片信息
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>JS 文件大小及类型判断</title>
<style>
*{ font-size:12px;}
*</style><script language="javascript">
<!--function ShowInfo(sUrl){ var FSO,F,Ext; var Extlist = ".gif.jpg.bmp"; //FSO = new ActiveXObject("Scripting.FileSystemObject"); //F = FSO.GetFile(sUrl); Ext = GetExt(sUrl); if(Extlist.indexOf(Ext)==-1) document.getElementById("Info").innerHTML = "扩展名：" + Ext + " 不是图片类型! 原始路径：" + sUrl; else{ document.getElementById("imgs").src = ""; document.getElementById("imgs").alt = "图片加载中……"; document.getElementById("imgs").src = sUrl; var MyImage = new Image(); MyImage.src = sUrl; document.getElementById("Info").innerHTML = "扩展名：" + Ext + " 合法图片类型! 原始路径：" + sUrl + "<br /> 文件大小：" + MyImage.fileSize + " Bytes 尺寸：" + MyImage.width + "*" + MyImage.height;
}}function GetExt(sUrl){ var arrList = sUrl.split("."); return arrList[arrList.length-1];}function DrawImage(ImgD,w,h){ var flag = false; var MyImage = new Image(); MyImage.src = ImgD.src; if(MyImage.readyState != "complete"){ return false; //确保图片完全加载 } if(MyImage.width > 0 && MyImage.height > 0){ flag = true; if(MyImage.width / MyImage.height >= w / h){ if(MyImage.width > w){ ImgD.width = w; ImgD.height = (MyImage.height * w) / MyImage.width; }else{ ImgD.width = MyImage.width; ImgD.height = MyImage.height; } ImgD.alt = "原始尺寸：" + MyImage.width + "x" + MyImage.height; }else{ if(MyImage.height > h){ ImgD.height = h; ImgD.width = (MyImage.width * h) / MyImage.height; }else{ ImgD.width = MyImage.width; ImgD.height = MyImage.height; } ImgD.alt = "原始尺寸：" + MyImage.width + "x" + MyImage.height; } }}function zoomimg(img){ var zoom=parseInt(img.style.zoom,10) || 100; zoom += event.wheelDelta / 24; imgW = img.clientWidth*zoom/100; if (zoom>10) img.style.zoom = zoom + "%"; return false;}
--></script></head><body><form id="form1" name="form1" enctype="multipart/form-data" method="post" action=""><p> <input name="ofile" type="file" id="ofile" onchange="ShowInfo(this.value);" /></p><p id="Info"></p><p><img src="#" id="imgs" width="300" height="300" onmousewheel="return zoomimg(this)" onload="DrawImage(this,300,300)" /></p></form></body></html>