jquery如何获取文件后缀

var file=$("input[name='file']").val(); 
var filename=file.replace(/.*(\/|\\)/, ""); 
var fileExt=(/[.]/.exec(filename)) ? /[^.]+$/.exec(filename.toLowerCase()) : '';

var location=$("input[name='file']").val(); 
     var point = location.lastIndexOf("."); 
       
     var type = location.substr(point); 
     if(type==".jpg"||type==".gif"||type==".JPG"||type==".GIF"){ 
                
     }

     var arr = sFileName.split('.');
     alert(arr[0]);

    var name= sFileName.substr(0,sFileName.length-4)

    var sFileName=sFile.replace(/.*(\/|\\)/, "");

<script > 
$(document).ready(function(){ 
 var a=$("#image").attr("src") 
 alert(a.replace(".png","")) 
 }) 
</script> 
<img alt="aaa" id="image" src="theImage.png" />