How to validate fileupload in javascript

you can use regular expression to get file extension like this:

var extens=(/[.]/.exec(myfile)) ? /[^.]+$/.exec(myfile) : undefined;

myfile is the address or the path of the file. This simply takes the part of the string after "." . Then you can place some control checks with if. Something like :

if(extens=="doc" || extens=="docx"|| extens=="xls")
{
//your method goes here
}
else
{
alert("file is invalid");
}

You can also refer to this for more help:

http://www.coursesweb.net/javascript/check-file-type-before-upload_t[^]

hope it helps :)