Object.create(null)

One of the funnest parts of JavaScript, or any programming language really, is that there are loads of tiny tricks and quirks that make the language that much more interesting.  I recently learned a nice fact about Object.create:  using null as the only argument to create an ultra-vanilla dictionary!

Object.create has been an awesome utility for prototype creation.  While that's nice, objects created with Object.create have __proto__ and inherited Object properties which can be manipulated.  What if you simply want a dictionary not prone to manipulation from the outside?  You can have that with Object.create(null):

let dict = Object.create(null);

// dict.__proto__ === "undefined"
// No object properties exist until you add them

Since there's no prototype your Object can't be manipulated from the outside -- it remains as vanilla of a dictionary as possible!  Compare that to Object.create({}):

let obj = Object.create({});

// obj.__proto__ === {}
// obj.hasOwnProperty === function

Object.prototype.someFunction = () => {};

// obj.someFunction === () => {};
// dict.someFunction === undefined

Passing Object.create an empty object allows for properties to be added via Object.prototype.customPropName, something you may not always want.

I hadn't known of this trick until recently but will be using it quite a bit going forward!