Reflect.set() - JavaScript 编辑

The static Reflect.set() method works like setting a property on an object.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Syntax

Reflect.set(target, propertyKey, value[, receiver])

Parameters

target

The target object on which to set the property.

propertyKey

The name of the property to set.

value

The value to set.

receiver Optional

The value of this provided for the call to target if a setter is encountered.

Return value

A Boolean indicating whether or not setting the property was successful.

Exceptions

A TypeError, if target is not an Object.

Description

The Reflect.set method allows you to set a property on an object. It does property assignment and is like the property accessor syntax as a function.

Examples

Using Reflect.set()

// Object
let obj = {}
Reflect.set(obj, 'prop', 'value')  // true
obj.prop  // "value"

// Array
let arr = ['duck', 'duck', 'duck']
Reflect.set(arr, 2, 'goose')  // true
arr[2]  // "goose"

// It can truncate an array.
Reflect.set(arr, 'length', 1)  // true
arr  // ["duck"]

// With just one argument, propertyKey and value are "undefined".
let obj = {}
Reflect.set(obj)  // true
Reflect.getOwnPropertyDescriptor(obj, 'undefined')
// { value: undefined, writable: true, enumerable: true, configurable: true }

Specifications

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

Browser compatibility

BCD tables only load in the browser

See also

• Reflect
• Property accessors