JavaScript Get upload file extension

When uploading a file to determine the type of the uploaded file meets the needs, access to upload the file extension using JavaScript. Presentation as follows:

    Source as follows:

1. <input size=30 type="file" name="pic" onchange="check_type(this)"/> 
2. <script language="javascript"> 
3. function check_type(obj){ 
4.         var  Cycle = $ (Obj) Kvl (); 
5.         var index=str.lastIndexOf('.'); 
6.         was  strtype = str.substr (index, 4); 
7.         strtype=strtype.toLowerCase(); 
8.         if(strtype!=".png" || strtype!=".jpg" || strtype!=".gif"){ 
9.             $(obj).val(""); 
10.             Alert ( "Please upload pictures gif, jpg, png format!" ); 
11.         } 
12.     } 
13. </script>
    

Reproduced in: https: //www.cnblogs.com/zhangchenliang/archive/2011/05/27/2060030.html