Reflect.has()
The static Reflect
.has()
method works like the in
operator as a function.
Syntax
JavaScript
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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()
JavaScript
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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
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Reflect.has' in that specification. |
Standard | Initial definition. |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Reflect.has' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 49 | 42 (42) | No support | No support | No support |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | No support | No support | 42.0 (42) | No support | No support | No support |
See also
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/javascript/reference/global_objects/reflect/has