foo.js

function wtf() {
  function doIt() {
    // Do the stuff here!
  }
  
  if (something) {
    var otherThing = somewhatExpensiveGetter(something);
    if (otherThing) {
      doIt();
    }
  }
  
  if (yetAnotherThing) {
    doIt();
  }
}