text: // undefined 
  typeof  undefinedValiable
  // string 
  
  typeof ""
  typeof ''
  
  // number 
  
  typeof 8
  
  //bolean
  
  typeof false
  
  // object
  typeof {name:"salvi", id:5268}
  
  //symbols
  
  //null?
  typeof null
  
  // array?
  
  typeof []
  
  // function ?
  var s= function(){}
  typeof s
  
  // other types 
  
  // NaN
  var a="welcome"
  var s = s/2;
  typeof s
  console.log(s)
  Number.isNaN(s)
  
  
  // do not use New except if you are convertimg type 
  new String()
  new Number()
  new Boolean()
  
  
  // others 
  
  var today = new Date("January 26,2020");
  today.toUTCString();
  today.toString();
  String(today);
  
  
  
  