Web/JavaScript/Reference/Global objects/Reflect/has

The static Reflect.has() method works like the in operator as a function.

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Syntax

Reflect.has(target, propertyKey)

Parameters

target: The target object in which to look for the property.
propertyKey: The name of the property to check.

Return value

A Boolean indicating whether or not the target has the property.

Exceptions

A TypeError, if target is not an Object.

Description

The Reflect.has method allows you to check if a property is in an object. It works like the in operator as a function.

Examples

Using Reflect.has()

Reflect.has({x: 0}, 'x')  // true
Reflect.has({x: 0}, 'y')  // false

// returns true for properties in the prototype chain 
Reflect.has({x: 0}, 'toString') 

// Proxy with .has() handler method
obj = new Proxy({}, {
  has(t, k) { return k.startsWith('door')  }
});
Reflect.has(obj, 'doorbell')  // true
Reflect.has(obj, 'dormitory')  // false

Reflect.has returns true for any inherited properties, like the in operator:

const a = {foo: 123}
const b = {__proto__: a}
const c = {__proto__: b}
// The prototype chain is: c -> b -> a
Reflect.has(c, 'foo') // true

Specifications

Specification
ECMAScript (ECMA-262)The definition of 'Reflect.has' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`has`	Chrome Full support 49	Edge Full support 12	Firefox Full support 42	IE No support No	Opera Full support 36	Safari Full support 10	WebView Android Full support 49	Chrome Android Full support 49	Firefox Android Full support 42	Opera Android Full support 36	Safari iOS Full support 10	Samsung Internet Android Full support 5.0	nodejs Full support 6.0.0

Legend

Full support: Full support
No support: No support