元编程

内部方法

Reflect 对象的方法

说明

[[GetPrototypeOf]]

.getPrototypeOf()

Determine the object that provides inherited properties for this object. A null value indicates that there are no inherited properties.

[[SetPrototypeOf]]

.setPrototypeOf()

Associate this object with another object that provides inherited properties. Passing null indicates that there are no inherited properties. Returns true indicating that the operation was completed successfully or false indicating that the operation was not successful.

[[IsExtensible]]

.isExtensible()

Determine whether it is permitted to add additional properties to this object.

[[PreventExtensions]]

.preventExtensions()

Control whether new properties may be added to this object. Returns true if the operation was successful or false if the operation was unsuccessful.

[[GetOwnProperty]]

.getOwnPropertyDescriptor()

Return a Property Descriptor for the own property of this object whose key is propertyKey, or undefined if no such property exists.

[[DefineOwnProperty]]

.defineProperty()

Create or alter the own property, whose key is propertyKey, to have the state described by PropertyDescriptor. Return true if that property was successfully created/updated or false if the property could not be created or updated.

[[HasProperty]]

.has()

Return a Boolean value indicating whether this object already has either an own or inherited property whose key is propertyKey.

[[Get]]

.get()

Return the value of the property whose key is propertyKey from this object. If any ECMAScript code must be executed to retrieve the property value, Receiver is used as the this value when evaluating the code.

[[Set]]

.set()

Set the value of the property whose key is propertyKey to value. If any ECMAScript code must be executed to set the property value, Receiver is used as the this value when evaluating the code. Returns true if the property value was set or false if it could not be set.

[[Delete]]

.deleteProperty()

Remove the own property whose key is propertyKey from this object. Return false if the property was not deleted and is still present. Return true if the property was deleted or is not present.

[[Enumerate]]

.enumerate()

Return an iterator object that produces the keys of the string-keyed enumerable properties of the object.

[[OwnPropertyKeys]]

.ownKeys()

Return a List whose elements are all of the own property keys for the object.

[[Call]]

.apply()

Executes code associated with this object. Invoked via a function call expression. The arguments to the internal method are a this value and a list containing the arguments passed to the function by a call expression. Objects that implement this internal method are callable.

[[Construct]]

.construct()

Creates an object. Invoked via the new or super operators. The first argument to the internal method is a list containing the arguments of the operator. The second argument is the object to which the new operator was initially applied. Objects that implement this internal method are called constructors. A function object is not necessarily a constructor and such non-constructor function objects do not have a [[Construct]] internal method.