JSPropertyDescriptor 编辑

A descriptor is used to declare whether an attribute can be written to whether it can delete an object that can enumerate and specify content.

Properties

A descriptor is an object that can have the following key values

Field Name	Description
getter	The get syntax binds an object property to a function that will be called when that property is looked up.
setter	The set syntax binds an object property to a function to be called when there is an attempt to set that property.
value	Describes the value of the specified property, which can be any valid Javascript value (function, object, string...)
configurable	Declare that the property can be modified and deleted
enumerable	Declare that the property can be enumerated, and the enumerable genus can be traversed by the for...in loop.
writable	Declare whether the specified attribute can be rewritten

Description

A descriptor is a property that describes an object's properties. There are two main types of property descriptors that exist in an object: a data descriptor and an access descriptor. You can use the Object.getOwnPropertyDescriptor() function to get the corresponding property of an object. Descriptor.

Examples

The following example demonstrates how to use the Object.defineProperty() function to create a property under an object in a javascript via a descriptor.

 

var language = {}; // Define an empty object language

Object.defineProperty(language, 'log', { // Define the log attribute under the language object
    value : ['CN','EN'],
    writable : true,
    enumerable : true,
    configurable : true
})

In the above example we defined a writable, deletable enumerable property.This is the same as the javascript directly defined property.

In other words, the above code is equivalent to the following code.

var language = {}; // Define an empty object language

languange.log = ['CN','EN']; // Define the log attribute under the language object