Is there an ES6+ alternative to doing Object.prototype.hasOwnProperty.call(obj, key)?

Question

The most bulletproof way of checking if an object has a certain key is:

Object.prototype.hasOwnProperty.call(obj, key)

This provides certain guarantees: it will only evaluate to true if key is a direct property of obj, and it will work even if obj doesn't have the usual Object as its prototype (for example, if it was created with const obj = Object.create(null)).

But it's a mouthful.

Is there any new syntax/method in ES6 or higher (including polyfillable or Babel-compilable 'proposals') that gives the same guarantees, but in a nicer, more readable way?

Answer 1

I'm not aware of any syntactical sugar for this. But you shouldn't need to use this very often¹, so writing it out occasionally shouldn't be too bad. An equivalent shorter version would be

({}).hasOwnProperty.call(obj, key)

If you really need to use it more often, just define a helper function:

const hasOwn = (obj, key) => Object.prototype.hasOwnProperty.call(obj, key);
const hasOwn = Function.prototype.call.bind(Object.prototype.hasOwnProperty);

_{1: In most cases, you can omit the check, use in instead, or should be using a Map with its comfortable has method.}