why not simulating a click on a hidden file input. mask by whatever you want for example
<div id="filenames" style="width:200px;height:200px;border:1px solid black;overflow:scroll;"></div>
<button onclick="document.getElementById('file').click ();">LoadFile</button>
<input type="file" id="file" style="display:none" onchange="var filediv=document.getElementById('filenames').appendChild (document.createElement ('p'));filediv.innerHTML=this.value;" />