Overrides the console.log (specifically this is for node.js) with an ISO timestamp prefix and still handles string interpolation formats.

console-log-format-timestamps.js

function showDate(){
  var date = new Date(), str = date.toISOString();
  return str;
}
function formatArgs(args){
    return util.format.apply(util.format, Array.prototype.slice.call(args));
}
var origLog = console.log;
console.log = function() {
  var strDate = " [ " + showDate() + " ] ";
  var logString = strDate + formatArgs(arguments);
  origLog(logString);
};