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
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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