Mastering Advanced JavaScript: The Ultimate Self-Assessment Quiz Quiz

1. Question 1

   In JavaScript, what will be logged to the console when executing the following code? nn let foo = { bar: 1 }; n Object.freeze(foo); n foo.bar = 2; n console.log(foo.bar);

   1. A: 1
   2. B: 2
   3. C: undefined
   4. D: null
   5. E: ReferenceError

2. Question 2

   Which statement about closures in JavaScript is correct?

   1. A: Closures can only access variables declared with let.
   2. B: Closures allow a function to access variables from its parent scope even after the parent function has closed.
   3. C: Closures create copies of variables from the outer function's scope.
   4. D: Closures are destroyed immediately after the function executes.
   5. E: Closures cannot access global variables.

3. Question 3

   Given the following code, which value will be shown by alert? nn var a = 1; n function f() { n var a = 2; n setTimeout(function() { alert(a); }, 0); n } n f();

   1. A: 1
   2. B: 2
   3. C: undefined
   4. D: It will throw an error
   5. E: NaN

4. Question 4

   What is the result of the following expression in JavaScript? nn 0.1 + 0.2 === 0.3

   1. A: true
   2. B: false
   3. C: undefined
   4. D: 'true'
   5. E: TypeError

5. Question 5

   Which of the following will NOT create a shallow copy of an array named arr in JavaScript?

   1. A: arr.slice()
   2. B: [...arr]
   3. C: Array.from(arr)
   4. D: arr.concat()
   5. E: arr.push()