prefer-object-has-own

Object.prototype.hasOwnProperty.call(user, key) is the long way to ask if a property belongs to the object itself. It's written like that so it also works on objects without a prototype. Object.hasOwn(user, key) does the same thing and says what it means.

The shorter spellings Object.hasOwnProperty.call() and {}.hasOwnProperty.call() are reported too.

--fix replaces everything before the arguments with Object.hasOwn.

Configure#

Off by default. To turn it on:

[lint.rules]
"prefer-object-has-own" = "error" # or "warn"

Examples#

if (Object.prototype.hasOwnProperty.call(user, "email")) {
  send(user.email);
}

const isSet = {}.hasOwnProperty.call(settings, key);
const isCached = Object.hasOwnProperty.call(cache, id);

if (Object.hasOwn(user, "email")) {
  send(user.email);
}

const isSet = Object.hasOwn(settings, key);
const isCached = Object.hasOwn(cache, id);

When not to use it#

Object.hasOwn is part of ES2022. Turn the rule off if your code runs on an older engine without a polyfill.