Object Instantiation

var o = new Object();

NO!

var o = new SpecializedObjConstructor();
var o = new Object();
var o = {};
var o = Object.create(proto, propDescriptors);

Object.create()

Object

.create(

    null,

    {

        property: {

            configurable: false,
            
            enumerable:   false,
            
            value:        undefined,

            writable:     false,

            get:          undefined,

            set:          undefined
        
        }

    }

);
`create` is a method on the `Object` constructor.

 

the first parameter is required and is an object to act as the newly created object's prototype. `null` is also a valid type here.

 

the second parameter is optional and is an object that defines how the new object's properties are configured.

configurable

If false (default:false), any attempts to delete the property or change the `configurable` descriptor will fail. `writable` and `enumerable` can still be changed.

enumerable

If false (default:false), the property will be NOT iterated over during a for..in (or similar) and will NOT be an item in the array returned by `Object.keys()`

writable

If false (default:false), the value of the property can not be changed.

value

the value of the property. If set (default:undefined), the `get` and `set` property descriptors must be undefined.

get

A getter function for the value. If set (default:undefined), the `value` property descriptor must be undefined.

set

A setter function for the value. If set (default:undefined), the `value` property descriptor must be undefined.

Datatype Emulation

Objects as Dictionaries

    uniqueKey : value
    .
    .
    .
{

  "twitter": "//twitter.com/uniqname",
    
  "linkedin": "//www.linkedin.com/profile/view?id=21174018",

  "github": "//github.com/uniqname"

}

that was easy!

Dictionary

Object

A dictionary (associative array, map, symbol table) is a data structure composed of a collection of key, value pairs.

Objects as Record

struct date {

   int year;

   int month;

   int day;

};
var date = {

    year: 1999,
    
    month: 12,

    day: 31

};

Watch this!

Record

Object

A record (struct, compound data) is a collection of elements, often fixed in number and sequence, indexed by names.

Objects as Sets

{

    "Cory",
    
    "Bruce",

    "Daniel"

}
{

    0: "Cory",
    
    1: "Bruce",

    2: "Daniel"

}

Watch this!

Set

Object

A data type that stores unordered and unduplicated values.

Objects as Arrays

[value, value, value, ...]
{

  0: "Cory",

  1: "Bruce",

  2: "Daniel",

  length: 3

}

Watch this!

Array

Object

A systematic arrangement of objects, usually in rows and columns

...continue

JS Fundamentals: Objects

By Cory Brown

JS Fundamentals: Objects

Objects are everywhere in JavaScript. One of the biggest "Ahha's" you'll have when learning JavaScript is that (almost) everything is an Object. Until then, You'll be bashing your head against your desk.

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