Load file by using html5

gistfile1.html

<input type="file" id="inputFile" />
<textarea id="output"></textarea>

<script>
  function readFile(evt) {
    var fs = evt.target.files;
    
    if(fs.length > 0) {
        var reader = new FileReader();
        reader.onload = function(e) {
            document.getElementById('output').innerText = reader.result;
        }
        
        reader.readAsText(fs[0]);
    }
}

document.getElementById('inputFile').addEventListener('change', readFile, false);
</script>