JavaScript MCQs – Introduction to JavaScript

21.) What is the output of the following code?

console.log(1 + "2" + 3);

22.) What is the result of the following code?

console.log(typeof NaN);

23.) What is the difference between == and === in JavaScript?

24.) What is the result of the following code?

let x = {};
let y = {};
console.log(x == y, x === y);

25.) What will the following code output?

(function() {
  var a = b = 5;
})();
console.log(typeof a, typeof b);

26.) Which of the following statements is true about the ‘this’ keyword in JavaScript?

27.) What will the following code output?

let obj = {
  a: 10,
  b: function() {
    return this.a + 20;
  }
};
let fn = obj.b;
console.log(fn(), obj.b());