SO fiddle

Test Fiddle mainly for SO Questions

by Nick Craver

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/overcast/jquery-ui.css">

JavaScript

var classes = { red: 'Red', green: 'Green' };

function prependObj(obj, prefix) {
  var result = {};
  for(var i in obj) if(obj.hasOwnProperty(i)) result[prefix+i] = obj[i];
  return result;
}

classes = prependObj(classes, "a-");
alert(JSON.stringify(classes));