text: /* var arr = [0,1,undefined]
  console.log(arr)
  console.log(arr[3])
  
  var obj = {name: "m", name1: undefined}
  console.log(obj)
  console.log(obj.h) */
  
  var a = +Infinity
  var b = -Infinity
  var c = NaN
  console.log(a, b,c)
  console.log(typeof(a), typeof(b), typeof(c))
  console.log(typeof(Math))
  console.log(typeof(Math.round()))
  console.log(typeof(Error))
  console.log(typeof(function(){}))