Wraps console.log to include a timestamp (in seconds since the wrapper was initialized) with every log message.

timestamped-console-log.js

console.log = (function() {
  var console_log = console.log;
  var timeStart = new Date().getTime();
  
  return function() {
    var delta = new Date().getTime() - timeStart;
    var args = [];
    args.push((delta / 1000).toFixed(2) + ':');
    for(var i = 0; i < arguments.length; i++) {
      args.push(arguments[i]);
    }
    console_log.apply(console, args);
  };
})();