Data Types in JavaScript

Program 1

//  console.log(typeof(a))  // undefined
//   b=10   // number
//   console.log(typeof(b))
//   c=10.56  //number
//   console.log(typeof(c))
//   d="Hello Friends"  //string
//   console.log(typeof(d))
//   e='Hello Friends' //string
//   console.log(typeof(e))
//   f=true  
//   console.log(typeof(f))
    
  //  let ar=[1,2,3,4,5,6,7,8,9]  // array is an object
  // console.log(typeof(ar))

    //  let st1={srno:101,sname:'Vivek',sper:98.55}
    //  console.log(typeof(st1))
    console.log("20"+10)