js判断上传文件的宽高,类型,filesize

<script type="text/javascript">

        UpLoadFileCheck = function () {
            this.AllowExt = ".jpg,.gif,.png,.jpeg"; //允许上传的文件类型 0为无限制 每个扩展名后边要加一个"," 小写字母表示
            this.AllowImgFileSize = 1; //允许上传文件的大小 0为无限制 单位：KB
            this.AllowImgWidth = 10; //允许上传的图片的宽度 0为无限制　单位：px(像素)
            this.AllowImgHeight = 10; //允许上传的图片的高度 0为无限制　单位：px(像素)
            this.ImgObj = new Image();
            this.ImgFileSize = 0;
            this.ImgWidth = 0;
            this.ImgHeight = 0;
            this.FileExt = "";
            this.ErrMsg = "";
            this.IsImg = false; //全局变量

        }

        UpLoadFileCheck.prototype.CheckExt = function (obj) {
            this.ErrMsg = "";
            this.ImgObj.src = obj.value;
            //this.HasChecked=false;  
            if (obj.value == "") {
                this.ErrMsg = "\n请选择一个文件";
            }
            else {
                this.FileExt = obj.value.substr(obj.value.lastIndexOf(".")).toLowerCase();
                if (this.AllowExt != 0 && this.AllowExt.indexOf(this.FileExt) == -1)//判断文件类型是否允许上传
                {
                    this.ErrMsg = "\n该文件类型不允许上传。请上传 " + this.AllowExt + " 类型的文件，当前文件类型为" + this.FileExt;
                }
            }
            if (this.ErrMsg != "") {
                this.ShowMsg(this.ErrMsg, false);
                return false;
            }
            else
                return this.CheckProperty(obj);
        }

        UpLoadFileCheck.prototype.CheckProperty = function (obj) {
            if (this.ImgObj.readyState != "complete")//
            {
                sleep(1000); //一秒使用图能完全加载    
            }

            if (this.IsImg == true) {
                this.ImgWidth = this.ImgObj.width; //取得图片的宽度
                this.ImgHeight = this.ImgObj.height; //取得图片的高度
                if (this.AllowImgWidth != 0 && this.AllowImgWidth < this.ImgWidth)
                    this.ErrMsg = this.ErrMsg + "\n图片宽度超过限制。请上传宽度小于" + this.AllowImgWidth + "px的文件，当前图片宽度为" + this.ImgWidth + "px";

                if (this.AllowImgHeight != 0 && this.AllowImgHeight < this.ImgHeight)
                    this.ErrMsg = this.ErrMsg + "\n图片高度超过限制。请上传高度小于" + this.AllowImgHeight + "px的文件，当前图片高度为" + this.ImgHeight + "px";
            }

            this.ImgFileSize = Math.round(this.ImgObj.fileSize / 1024 * 100) / 100; //取得图片文件的大小  
            if (this.AllowImgFileSize != 0 && this.AllowImgFileSize < this.ImgFileSize)
                this.ErrMsg = this.ErrMsg + "\n文件大小超过限制。请上传小于" + this.AllowImgFileSize + "KB的文件，当前文件大小为" + this.ImgFileSize + "KB";

            if (this.ErrMsg != "") {
                this.ShowMsg(this.ErrMsg, false);
                return false;
            }
            else
                return true;
        }

        UpLoadFileCheck.prototype.ShowMsg = function (msg, tf)//显示提示信息 tf=false 显示错误信息 msg-信息内容
        {
            /*msg=msg.replace("\n","<li>");
            msg=msg.replace(/\n/gi,"<li>");
            */
            alert(msg);
        }
        function sleep(num) {
            var tempDate = new Date();
            var tempStr = "";
            var theXmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
            while ((new Date() - tempDate) < num) {
                tempStr += "\n" + (new Date() - tempDate);
                try {
                    theXmlHttp.open("get", "about:blank?JK=" + Math.random(), false);
                    theXmlHttp.send();
                }
                catch (e) { ; }
            }
            //containerDiv.innerText=tempStr;  
            return;
        }

        function c(obj) {
            var d = new UpLoadFileCheck();
            d.IsImg = true;
            d.AllowImgFileSize = 100;
            d.CheckExt(obj)
        }
        //调用 <input name="" type="file" onchange="c(this)" />
    </script>

<script type="text/javascript">
function ajaxFunction()
{
  var xmlHttp;
  try
{
    // Firefox, Opera 8.0+, Safari
    xmlHttp=new XMLHttpRequest();
}
  catch (e)
{
    // Internet Explorer
    try
    {
      xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch (e)
    {
      try
      {
        xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch (e)
      {
        alert("您的浏览器不支持AJAX!");
        return false;
      }
    }
}
}
</script>