Object Oriented JavaScript optimization

This is a simple script that I use for wrapping a selected word in a textarea field. I'm looking to:

1. make sure my logic is valid/see what others have done in a relative context.

2. request improvements to the OO approach I'm going for.

Formatter = {};

Formatter.getSelection = function(event) {
  var text  = document.getElementById("mass_message");
  var sPos  = text.selectionStart;
  var ePos  = text.selectionEnd;
  var front = (text.value).substring(0, sPos);
  var sel   = (text.value).substring(sPos, ePos);
  var back  = (text.value).substring(ePos, text.value.length);
  format    = event.data.format;

  var print = Formatter.setString(text, format, front, back, sel);
}

Formatter.setString = function(text, format, front, back, sel) {
  text.value = front + "<" + format + ">" + sel + "</" + format + ">" + back;
}

$(document).ready(function(){
  $( '#bolden' ).on('click', { format: "b" }, Formatter.getSelection);
  $( '#italicize' ).on('click', { format: "i" }, Formatter.getSelection);
});

I'm appreciative of any suggestions and am happy to answer questions about the code.