function behavior(config) {
  return function () {
    if (config.verbose) {
      console.log('I AM SCREAMING!');
    } else {
      console.log('i am a bit more polite');
    }
  }
}

var talk = behavior({verbose: true});
talk();

--------------------------------------------


function behavior2(config) {
  if (config.verbose) {
    console.log('I AM SCREAMING!');
  } else {
    console.log('i am a bit more polite');
  }
}

var talk = behavior2.bind(null, {verbose: true});
talk();