prefer-object-has-own.md

Prefer Object.hasOwn() over Object.prototype.hasOwnProperty.call() (prefer-object-has-own)

Object.hasOwn() is more accessible than Object.prototype.hasOwnProperty.call().

It is recommended over Object#hasOwnProperty() because it works for objects created using Object.create(null) and with objects that have overridden the inherited hasOwnProperty() method.

const foo = {
  hasOwnProperty: function() {
    return false;
  },
  bar: 'Hello World'
};

console.log(Object.hasOwn(foo, 'bar')); // true - re-implementation of hasOwnProperty() does not affect Object

const bar = Object.create(null);
bar.prop = 'exists';

console.log(Object.hasOwn(bar, 'prop')); // true - works irrespective of how the object is created.

Rule Details

Examples of incorrect code for this rule:

/*eslint prefer-object-has-own: "error"*/

Object.prototype.hasOwnProperty.call(obj, "a");

Object.hasOwnProperty.call(obj, "a");

({}).hasOwnProperty.call(obj, "a");

const hasProperty = Object.prototype.hasOwnProperty.call(object, property);

Examples of correct code for this rule:

/*eslint prefer-object-has-own: "error"*/

Object.hasOwn(obj, "a");

const hasProperty = Object.hasOwn(object, property);

When Not To Use It

This rule should not be used unless ES2022 is supported in your codebase.

Further Reading

• Object.hasOwn()