Javascript Basics Part III


  • An object is an unordered collection of name/value pairs
  • Names are strings
  • Values are any type, including other objects
  • Every object is a little database

Object Literals

  • Object literals are wrapped in {}
  • Values can be expressions
  • : separate names and values
  • , separates pairs
  • Can be used anywhere value is required
  • New members can be added to any object by simple assignment myObject[name]=value

Maker function

function maker(name, where)
	var it={};;
	return it;

myObject = maker("Madhur Ahuja", "Jail");


  • Objects can be created with a secret link to another object
  • The object(o) function will be used with a secret link to object o
  • The linkage cannot be changed once created. It is possible in Mozilla implementation, but is non-standard.

var myNewObject = object (myOldObject);

  • All objects are linked to Object.prototype
  • All objects inherit some methods, none of them are useful
  • Objects doesn’t have copy or equals methods. Omission from the language.

Object construction##

  1. new Object()
  2. {}
  3. object(Object.protype)
  • Second is the most preferred

  • Objects are passed by reference
  • === or == compares references not values

  • members can be removed by using delete operator


  • Inherits from object
  • No need to provide a length or type when creating array
  • Have a special length member
  • Array literal uses []
  • myList = ['Oats' , 'peas']
  • New items can be added myList[myList.length]='barley'
  • The dot notation cannot be used. Should use subscript notation
  • Methods: concat, join, pop, push, slice, sort , splice
  • delete array[number] Removes the element, but leaves the hole
  • array.splice(number, 1) Removes the element and renumbers all the following elements
  • Use objects when names are arbitrary strings
  • Use arrays when names are sequential integers