HTML5 JS that allows saving and loading client side of any textarea. The example assume jQuery but fileio.js does not need jQuery.

fileio.js

/* example:

  <script src='fileio.js'>
  <script>FileIO.check_browser()</script>
  <textarea id="code">
    hello world
  </textarea>  
  <a href="#" id="load-button">Load</a>
  <a href="#" id="save-button" onclick="FileIO.save(jQuery('#code').val())">Save</a>
  <script>FileIO.load('load-button',function(f){jQuery('#code').val(f.result)})</script>

*/

var FileIO = {
    check_browser: function(callback) {
         if(!(window.File && window.FileReader && window.FileList && window.Blob)) {
             callback || alert('Sorry, your browser is not supported. Try Chrome!');
         }
    },
    save: function(data, name) {
        if(!name) name = prompt('Save As');
        if(!name) return;
        var data = 'data:application/octet-stream;base64,' + btoa( data );
        var node = document.createElement('a');
        node.download = name || self.location.pathname.slice(self.location.pathname.lastIndexOf('/')+1);
        node.href = data || self.location.href;
        var ev = document.createEvent("MouseEvents");
        ev.initMouseEvent("click", true, false, self, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
        return node.dispatchEvent(ev);
    },
    load: function(id, loader) {
        var handleFileSelect = function(evt) {
          var files = evt.target.files;
          // Loop through the FileList and render image files as thumbnails.
          for (var i = 0, f; f = files[i]; i++) {
            var reader = new FileReader();
            reader.onload = function(e) { loader(e.target); }
            reader.readAsBinaryString(f);
          }
        }
        document.getElementById(id).addEventListener('change', handleFileSelect, false);
   }
};