reflect-js

Extended reflection for Node JS

About

Reflect-js expands on the Reflect object
to provide additional capability.

API

In addition to the API provided by Reflect, Reflect-js provides:
* getOwnConstructorDescriptor(target: object) => MethodDescriptor
* getOwnDescriptor(target: object, name: string) => Descripitor
* getOwnDescriptors(target: object, methods?: boolean) => Array
* getOwnFieldDescriptors(target: object) => Array
* getOwnKeys(target: object, methods?: boolean) => Array
* getOwnMethodDescriptors(target: object) => Array
* getOwnPropertyDescriptors(target: object) => Array

$3

Most Reflect-js methods return instances of the Descriptor interface:
~~~~
Descriptor {
configurable: boolean,
enumerable: boolean,
name: string,
value: any,
writable: boolean
}
~~~~

The FieldDescriptor, MethodDescriptor and PropertyDescriptor classes implement the Descriptor interface.

~~~~
FieldDescriptor {
configurable: boolean,
enumerable: boolean,
name: string,
value: any,
writable: boolean
}
~~~~

~~~~
MethodDescriptor {
arguments: Array,
configurable: boolean,
enumerable: boolean,
name: string,
value: function,
writable: boolean
}
~~~~

~~~~
PropertyDescriptor {
configurable: boolean,
enumerable: boolean,
getter: MethodDescriptor | null,
name: string,
readable: boolean,
setter: MethodDescriptor | null,
value: any,
writable: boolean
}
~~~~

$3

``getOwnConstructorDescriptor(target: object) => MethodDescriptor`

Gets the MethodDescriptor for the constructor.

Usage:
~~~~
const ReflectExt = require('reflect-js');
class Person {
constructor(name, age) {
this.name = name;
this.age = age;
}
get birthYear() {
return new Date.getUTCFullYear() - this.age;
}
}
var michael = new Person('Michael', 46);
ReflectExt.getOwnConstructorDescriptor(michael);
/*
MethodDescriptor {
enumerable: false,
configurable: true,
writable: true,
value: [Function: Person],
name: 'constructor',
arguments: [ 'name', 'age' ] }
*/
~~~~

$3

`getOwnDescriptor(target: object, name: string) => Descripitor`

Gets a Descriptor object for the requested field, property or method of the target, or null if the name is not a member of the target.

Usage:
~~~~
const ReflectExt = require('reflect-js');
class Person {
constructor(name, age) {
this.name = name;
this.age = age;
}
get birthYear() {
return new Date.getUTCFullYear() - this.age;
}
}
var michael = new Person('Michael', 46);
ReflectExt.getOwnDescriptor(michael, 'birthYear');
/*
PropertyDescriptor {
enumerable: false,
configurable: true,
writable: false,
value: undefined,
name: 'birthYear',
readable: true,
getter:
MethodDescriptor {
enumerable: false,
configurable: true,
writable: false,
value: [Function: get birthYear],
name: 'get birthYear',
arguments: [] },
setter: null }
*/
~~~~

$3

`getOwnDescriptors(target: object, methods?: boolean) => Array`

Gets all the Descriptors for the target object. If methods is false, just gets the fields.

Usage:
~~~~
const ReflectExt = require('reflect-js');
class Person {
constructor(name, age) {
this.name = name;
this.age = age;
}
get birthYear() {
return new Date.getUTCFullYear() - this.age;
}
}
var michael = new Person('Michael', 46);
ReflectExt.getOwnDescriptors(michael);
/*
[ FieldDescriptor {
enumerable: true,
configurable: true,
writable: true,
value: 'Michael',
name: 'name' },
FieldDescriptor {
enumerable: true,
configurable: true,
writable: true,
value: 46,
name: 'age' },
MethodDescriptor {
enumerable: false,
configurable: true,
writable: true,
value: [Function: Person],
name: 'constructor',
arguments: [ 'name', 'age' ] },
PropertyDescriptor {
enumerable: false,
configurable: true,
writable: false,
value: undefined,
name: 'birthYear',
readable: true,
getter:
MethodDescriptor {
enumerable: false,
configurable: true,
writable: false,
value: [Function: get birthYear],
name: 'get birthYear',
arguments: [] },
setter: null } ]
*/
~~~~

$3

`getOwnFieldDescriptors(target: object) => Array`

Gets the FieldDescriptors of the target. It is implemented as:
`getOwnDescriptors(target).filter(descriptor => descriptor instanceof FieldDescriptor)`

See getOwnDescriptors for usage.

$3

`getOwnKeys(target: object, methods?: boolean) => Array`

Gets field names, property names and method names. If methods is missing or
true, inspects the constructor prototype (the class).

Usage:
~~~~
const ReflectExt = require('reflect-js');
class Person {
constructor(name, age) {
this.name = name;
this.age = age;
}
get birthYear() {
return new Date.getUTCFullYear() - this.age;
}
}
var michael = new Person('Michael', 46);
ReflectExt.getOwnKeys(michael); // => ['name', 'age', 'constructor', 'birthYear']
~~~~

$3

`getOwnMethodDescriptors(target: object) => Array`

Gets the MethodDescriptors of the target. It is implemented as:
`getOwnDescriptors(target).filter(descriptor => descriptor instanceof MethodDescriptor && descriptor.name !== 'constructor')`

See getOwnDescriptors for usage.

$3

`getOwnPropertyDescriptors(target: object) => Array`

Gets the PropertyDescriptors of the target. It is implemented as:
`getOwnDescriptors(target).filter(descriptor => descriptor instanceof PropertyDescriptor)``

See getOwnDescriptors for usage.