gistfile1.js

Object.extend(NativeObject.prototype, function() {

  function computeSomethingWhenAwesomeCapabilityIsAvailable() {
    // ...
  }

  function computeSomethingWhenSomeStupidIEBugIsPresent() {
    // ...
  }
  
  function computeSomethingTheNormalWay() {
    // ...
  }

  var computeSomething = computeSomethingTheNormalWay;
  if (testForCapability()) {
    computeSomething = computeSomethingWhenAwesomeCapabilityIsAvailable;
  } else if (testForStupidIEBug()){
    computeSomething = computeSomethingWhenSomeStupidIEBugIsPresent;
  }

  return {
    computeSomething: computeSomething
  };
}());