JavaScript Object

Terms

• Constructor function

  : A JavaScript function that creates an object through the new operator and creates and initializes properties and methods

• Prototype

  • A property of the constructor function

  • The place where properties and methods that are identically inherited by objects created by the constructor function are defined

• Private member

  : A property or method that cannot be modified from outside the object

JavaScript Object

• All data types except Primitive data types are Objects

  • Primitive Types

    • number

    • string

    • boolean

    • null

      : no value

    • undefined

      : a declared variable, but hasn't been given a value

    • symbol

      : a unique value that's not equal to any other value

• Functions are also objects

Object Creation

Object

: A collection of properties

Object Creation

• When using an object literal, the object is created by listing its properties

• Empty object

  : Used because properties can be easily added when creating functions with the literal method

• namespace

  : Minimizes the use of global variables by converting variables and functions into object properties

• Objects are created using the new operator and constructor functions

Constructor Functions and prototype

• this

  : Used in methods and refers to the calling object that invoked the method

• Constructor function

  • A function that defines what properties an object to be created will have and how those properties will be initialized

  • Similar to classes in typical object-oriented languages

• prototype

  • Means that the properties of an object are not copied to the created object but are referenced

  • If the prototype object of the constructor function is modified, the properties of objects created by this constructor function are changed!