js判断文件大小利用img 的 dynsrc，兼容IE10 及以上

2024-02-19 17:30:22
原文链接

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
 <head>
 
 
 <meta name="DEscription" contect="my code demo" />
 <meta name="Author" contect="Michael@jb51.net" />
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
 <meta http-equiv="X-UA-Compatible" content="IE=emulateIE8">
 <title>js check file size @ jb51.net</title>
 </head>
 <body>
 < img id="tempimg" dynsrc="" src="" style="display:none" />
 <input type="file" name="file" id="fileuploade" size="40" />
 <input type="button" name ="check" value="checkfilesize" οnclick="checkfile()"/>
 </body>
 <script type="text/javascript">
 var maxsize = 210241024;//2M
 var errMsg = "上传的附件文件不能超过2M！！！";
 var tipMsg = "您的浏览器暂不支持计算上传文件的大小，确保上传文件不要超过2M，建议使用IE、FireFox、Chrome浏览器。";
 var browserCfg = {};
 var ua = window.navigator.userAgent;
 if (ua.indexOf("MSIE")>=1){
 browserCfg.ie = true;
 }else if(ua.indexOf("Firefox")>=1){
 browserCfg.firefox = true;
 }else if(ua.indexOf("Chrome")>=1){
 browserCfg.chrome = true;
 }
 function checkfile(){
 try{
 var obj_file = document.getElementById("fileuploade");
 if(obj_file.value==""){
 alert("请先选择上传文件");
 return;
 }
 var filesize = 0;
 if(browserCfg.firefox || browserCfg.chrome ){
 filesize = obj_file.files[0].size;
 }else if(browserCfg.ie){
 var obj_img = document.getElementById('tempimg');
 obj_img.dynsrc=obj_file.value;
 filesize = obj_img.fileSize; 
 alert(filesize);
 }else{
 alert(tipMsg);
 
 return;
 }
 if(filesize==-1){
 alert(tipMsg);
 return;
 }else if(filesize>maxsize){
 alert(errMsg);
 return;
 }else{
 alert("文件大小符合要求");
alert(filesize);
 return;
 }
 }catch(e){
 alert(e);
 }
 }
 </script>
</html>
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