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This is a new technology, part of the ECMAScript 2015 (ES6) standard .
This technology's specification has been finalized, but check the compatibility table for usage and implementation status in various browsers.
The static Reflect.has() method works like the in operator as a function.
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.
Errors thrown
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
Specifications
| Specification | Status | Comment |
|---|---|---|
| ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Reflect.has' in that specification. |
Standard | Initial definition. |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | Not supported | 42 (42) | Not supported | Not supported | Not supported |
| Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | Not supported | Not supported | 42.0 (42) | Not supported | Not supported | Not supported |