Allow only pdf, doc, docx format for file upload?

Better to use change event on input field.

Updated source:

var myfile="";

$('#resume_link').click(function( e ) {
    e.preventDefault();
    $('#resume').trigger('click');
});

$('#resume').on( 'change', function() {
   myfile= $( this ).val();
   var ext = myfile.split('.').pop();
   if(ext=="pdf" || ext=="docx" || ext=="doc"){
       alert(ext);
   } else{
       alert(ext);
   }
});

Updated jsFiddle.

For only acept files with extension doc and docx in the explorer window try this

    <input type="file" id="docpicker"
  accept=".doc,.docx,application/msword,application/vnd.openxmlformats-officedocument.wordprocessingml.document">

You can use

<input name="Upload Saved Replay" type="file" 
  accept="application/pdf,application/msword,
  application/vnd.openxmlformats-officedocument.wordprocessingml.document"/>

whearat

• application/pdf means .pdf
• application/msword means .doc
• application/vnd.openxmlformats-officedocument.wordprocessingml.document means .docx

instead.

[EDIT] Be warned, .dot might match too.