js判断文件格式及大小的简单实例(必看)

//判断照片大小function getPhotoSize(obj){  photoExt=obj.value.substr(obj.value.lastIndexOf(".")).toLowerCase();//获得文件后缀名  if(photoExt!='.jpg'){    alert("请上传后缀名为jpg的照片!");    return false;  }  var fileSize = 0;  var isIE = /msie/i.test(navigator.userAgent) && !window.opera;        if (isIE && !obj.files) {          var filePath = obj.value;           var fileSystem = new ActiveXObject("Scripting.FileSystemObject");       var file = fileSystem.GetFile (filePath);             fileSize = file.Size;       }else {      fileSize = obj.files[0].size;     }   fileSize=Math.round(fileSize/1024*100)/100; //单位为KB  if(fileSize>=10){    alert("照片最大尺寸为10KB，请重新上传!");    return false;  }}

<input type="file" id="imgFile" name="upload" style="width:150px;" onchange="getPhotoSize(this)"/>