// C#
var customer = new Customer(); //var is compiler inferred

//Javascript
var customer = new Customer(); //var is variable declaration

//C#

var x = 0; // compiler暗示 to be int
bool isInt = x is int;  //x是int类型，右边是true
x = new object();  //C#定义过的变量需要保持typ

//Javascript

var x = 0; //creates variable x that holds a number
bool isNumber = typeof x == "number";  //works but limited
x = new object();  // no problem, can redefie the x with new type

//C#
class Dog : Animal, IMoveable {...}
class Car : Vehicle, IMoveable {...}

//Accept any animal (base class has Feed Methord)
void Feed(Animal ani) {ani.Feed();}


//Accept any object that implements interface
void Move(IMoveable object) {object.Move();}

//JavaScript

//Accept any object
//(must implement Feed function)
functionFeed(ani) {ani.Feed();}


//Accept any object 
//must implement move methord
function Move(object) {object.Move();}

//JavaScript

var a = typeof 1;                //number
var b = typeof 1.0;              //number
var c = typeof true;            //true
var d = typeof false;            //false
var e = typeof "hello world"    //string

//javascript

var x = 1;
var typeName = typeof x;  //"number"