function getType(obj) {
  return Object.prototype.toString.call(obj).slice(8, -1);
}

let num = 1;
console.log(getType(num)); // "Number"

let str = "Hello World";
console.log(getType(str)); // "String"

let arr = [1, 2];
console.log(getType(arr)); // "Array"

let obj = { name: "sand" };
console.log(getType(obj)); // "Object"

let func = function() {};
console.log(getType(func)); // "Function"

let n = null;
console.log(getType(n)); // "Null"

let u = undefined;
console.log(getType(u)); // "Undefined"