Skip to content

Object.js.md

Latest commit

 

History

History
215 lines (163 loc) · 7.45 KB

Object.js.md

File metadata and controls

215 lines (163 loc) · 7.45 KB

Object

🎗️ TODO: ==Complete this!== It's not done!

The Object constructor` creates an object wrapper.

[toc]

Diagram

⛽ YMMV: Depending on what markdown editor you use, you may have mermaid features or not. Mermaid also doesn't have proper UML notation for abstract and static properties and methods. For now, static features (which should be underlined) end with a dollar sign and abstract features (which should be italic) end with an asterisk.

classDiagram
Function <|-- Object
class Function
class Object {
	+Number length$ = 1
	+Object prototype$
	+Object assign()$
	+Object create()$
	+Object defineProperty()$
	+Object defineProperties()$
	+Array entries()$
	+freeze()$
	+Object fromEntries(kvarr : Array)$
	+Object getOwnPropertyDescriptor()$
	+Array getOwnPropertyDescriptors()$
	+Array getOwnPropertyNames()$
	+Array getOwnPropertySymbols()$
	+getPrototypeOf()$
	+Boolean is()$
	+Boolean isExtensible()$
	+Boolean isFrozen()$
	+Boolean isSealed()$
	+Array keys()$
	+preventExtensions()$
	+seal()$
	+setPrototypeOf()$
	+Array values()$
	+Object constructor
	+Boolean hasOwnProperty()
	+Boolean isPrototypeOf()
	+Boolean propertyIsEnumerable()
	+String toLocaleString()
	+String toString()
	+String valueOf()
}
Loading

Syntax

// Object initializer or literal
{ [ nameValuePair1[, nameValuePair2[, ...nameValuePairN ]]] }

// Called as a constructor
new Object([value])

Parameters

nameValuePair1, nameValuePair2, ...nameValuePairN
Pairs of names (strings) and values (any value) where the name is separated by the value by a colon.
value
Any value

Description

The Object constructor creates an object wrapper for the given value.

When called in a non-constructor context, Object behaves identical to new Object().

Static Properties

Object.length
Has a value of 1.
Object.prototype
Allows the addition of properties to all objects of type Object.

Static Methods

Object.assign() : Object
Copies the values of all enumerable own properties from one or more source object to a target object.
Object.create() : Object
Creates a new object with the specified prototype object and properties.
Object.defineProperty()
Adds the named property described by a given descriptor to an object.
Object.defineProperties()
Adds the named properties described by the given descriptors to an object.
Object.entries(kvobj : Object) : Array
Returns an array containing all the [key, value] pairs in a given object's own enumerable string properties.
Object.freeze(obj : Object) : Object
Freezes an object. Other code cannot delete or change its properties.
Object.fromEntries(kvarr : Array) : Object
Return a new object from an iterable of [key, value] pairs.(The reverse of Object.entries().)
Object.getOwnPropertyDescriptor()
Returns a property descriptor for a named property or an object.
Object.getOwnPropertyDescriptors() : Object
Returns an object containing all own property descriptors for an object.
Object.getOwnPropertyNames() : Array
Return an array containing the names of all the given object's own enumerable and nonenumerable properties.
Object.getOwnPropertySymbols() : Array
Returns an array of all symbol properties found directly upon a given object.
Object.getPrototypeOf()
Returns the prototype of the specified object.
Object.is() : Boolean
Compares if two values are the same value. Equates all NaNvalues (which differ from both Abstract Equality Comparison (==) and Strict Equality comparison (===)).
Object.isExtensible() : Boolean
Determines if extending of an object is allowed.
Object.isFrozen() : Boolean
Determines if an object was frozen.
Object.isSealed() : Boolean
Determines if an object is sealed.
Object.keys(kvobj : Object) : Array
Returns an array containing the names of all the given object's own enumerable string properties.
Object.preventExtensions(obj : Object) : Object
Prevents an extensions of an object.
Object.seal(obj : Object) : Object
Prevents other code from deleting properties of an object.
Object.setPrototypeOf()
Sets the object's prototype (its internal [[Prototype]] property.)
Object.values(kvobj : Object) : Array
Returns an array containing the values that correspond to all of a given object's own enumerable string properties.

Instance Properties

Object.prototype.constructor : Object
Specifies the function that creates an object's prototype.

Instance Methods

Object.prototype.hasOwnProperty() : Boolean
Return a boolean indicating whether an object contains the specified property as a direct property of that object and not inherited through the prototype chain.
Object.prototype.isPrototypeOf() : Boolean
Returns a boolean indicating whether the object this method is called upon is in the prototype chain of the specified object.
Object.prototype.propertyIsEnumerable() : Boolean
Return a boolean indicating if the internal ECMAScript [[Enumerable]] attribute is set.
Object.prototype.toLocaleString() : String
Calls toString()
Object.prototype.toString() : String
Returns a string representation of the object.
Object.prototype.valueOf() : String
Returns the primitive value of teh specified object.

Special

Deleting a property from an object

There isn't any method in an Object itself to delete its own property (such as Map.prototype.delete()). To do so, one must use the delete operator.

🎗️ TODO: How?

Examples

Using Object given undefined or null types.

The following examples store an empty Object object in o:

let o = new Object();
let o = new Object(undefined);
let o = new Object(null);

Using Object to create Boolean objects.

The following examples store Boolean objects in o:

let o = new Object(true);		// equivalent to o = new Boolean(true);
let o = new Object(Boolean());	// equivalent to o = new Boolean(false);

References