当前位置：文江博客知识库 en-US 文档 Web JavaScript Reference Global_Objects Reflect Comparing_Reflect_and_Object_methods

Comparing Reflect and Object methods - JavaScript 编辑

The Reflect object, introduced in ES2015, is a built-in object that provides methods to interface with JavaScript objects. Some of the static functions that exist on Reflect also correspond to methods available on Object, which predates ES2015. Although some of the methods appear to be similar in their behavior, there are often subtle differences between them.

The table below details the differences between the methods available on the Object and Reflect APIs. Please note that if a method does not exist in an API, it is marked as N/A.

Method Name	`Object`	`Reflect`
`defineProperty()`	`Object.defineProperty()` returns the object that was passed to the function. Returns a `TypeError` if the property was not successfully defined on the object.	`Reflect.defineProperty()` returns `true` if the property was defined on the object and `false` if it was not.
`defineProperties()`	`Object.defineProperties()` returns the objects that were passed to the function. Returns a `TypeError` if any properties were not successfully defined on the object.	N/A
`set()`	N/A	`Reflect.set()` returns `true` if the property was set successfully on the object and `false` if it was not. Throws a `TypeError` if the target was not an `Object`.
`get()`	N/A	`Reflect.get()` returns the value of the property. Throws a `TypeError` if the target was not an `Object`.
`deleteProperty()`	N/A	`Reflect.deleteProperty()` returns `true` if the property was deleted from the object and `false` if it was not.
`getOwnPropertyDescriptor()`	`Object.getOwnPropertyDescriptor()` returns a property descriptor of the given property if it exists on the object argument passed in, and returns `undefined` if it does not exist. However, if an object is not passed in as the first argument, it will be coerced into an object.	`Reflect.getOwnPropertyDescriptor()` returns a property descriptor of the given property if it exists on the object. Returns `undefined` if it does not exist, and a `TypeError` if anything other than an object (a primitive) is passed in as the first argument.
`getOwnPropertyDescriptors()`	`Object.getOwnPropertyDescriptors()` returns an object containing a property descriptor of each passed-in object. Returns an empty object if the passed-in object has no owned property descriptors.	N/A
`getPrototypeOf()`	`Object.getPrototypeOf()` returns the prototype of the given object. Returns `null` if there are no inherited properties. Throws a `TypeError` for non-objects in ES5, but coerces non-objects in ES2015.	`Reflect.getPrototypeOf()` returns the prototype of the given object. Returns `null` if there are no inherited properties, and throws a `TypeError` for non-objects.
`setPrototypeOf()`	`Object.setPrototypeOf()` returns the object itself if its prototype was set successfully. Throws a `TypeError` if the prototype being set was anything other than an `Object` or `null`, or if the prototype for the object being modified is non-extensible.	`Reflect.setPrototypeOf()` returns `true` if the prototype was successfully set on the object and `false` if it wasn't (including if the prototype is non-extensible). Throws a `TypeError` if the target passed in was not an `Object`, or if the prototype being set was anything other than an `Object` or `null`.
`isExtensible()`	`Object.isExtensible()` returns `true` if the object is extensible, and `false` if it is not. Throws a `TypeError` in ES5 if the first argument is not an object (a primitive). In ES2015, it will be coerced into a non-extensible, ordinary object and will return `false`.	`Reflect.isExtensible()` returns `true` if the object is extensible, and `false` if it is not. Throws a `TypeError` if the first argument is not an object (a primitive).
`preventExtensions()`	`Object.preventExtensions()` returns the object that is being made non-extensible. Throws a `TypeError`in ES5 if the argument is not an object (a primitive). In ES2015, treats the argument as a non-extensible, ordinary object and returns the object itself.	`Reflect.preventExtensions()` returns `true` if the object has been made non-extensible, and `false` if it has not. Throws a `TypeError` if the argument is not an object (a primitive).
`keys()`	`Object.keys()` returns an `Array` of strings that map to the target object's own (enumerable) property keys. Throws a `TypeError` in ES5 if the target is not an object, but coerces non-object targets into objects in ES2015.	N/A
`ownKeys()`	N/A	`Reflect.ownKeys()` returns an `Array` of property names that map to the target object's own property keys. Throws a `TypeError` if the target is not an `Object`.