Javascript editor in your browser

editor.html

data:text/html,
<style type="text/css">
#e {
  position:absolute;
  top:0;
  right:0;
  bottom:0;
  left:0;
  font-size:16px;
}
</style>
<div id="e"></div>
<script src="http://d1n0x3qji82z53.cloudfront.net/src-min-noconflict/ace.js"></script>
<script src="http://code.jquery.com/jquery-1.9.0.min.js"></script>
<script>
var myKey="SecretKeyz";
$(document).ready(function(){
    var e = ace.edit("e");
    e.setTheme("ace/theme/tomorrow_night_eighties");
    e.getSession().setMode("ace/mode/javascript");
    
    var url = "http://api.openkeyval.org/"+myKey;
    $.ajax({
      url: url,
      dataType: "jsonp",
      success: function(data){
       e.setValue(data);
      }
    });

    $("#e").on("keydown", function (b) {
      if (b.ctrlKey && 83 == b.which) {
        // Save to OpenKeyVal
        b.preventDefault();
        var data = myKey+"="+encodeURIComponent(e.getValue());
        $.ajax({
          data: data,
          url: "http://api.openkeyval.org/store/",
          dataType: "jsonp",
          success: function(data){
            alert("Saved.");
          }
        });
      } else if (b.ctrlKey && 74 == b.which) {
        // Execute Current Buffer
        b.preventDefault();
        eval(e.getValue());
      }
    });
});
</script>

Use Ace editor, set to JavaScript mode and use ctrl+j to execute current buffer.