Call stack behavior in Javascript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to call the function named greet.

Javascript

function greet() {
  console.log('Hello!');
}

greet[1];

Drag options to blanks, or click blank then click option'

A()

B[]

C{}

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets instead of parentheses.

Forgetting to add parentheses, so the function is not called.

To call a function in JavaScript, you use parentheses () after the function name.

2fill in blank

medium

Complete the code to log the value returned by the function add.

Javascript

function add(a, b) {
  return a + b;
}

console.log(add[1]);

Drag options to blanks, or click blank then click option'

A{2, 3}

B(2, 3)

C[2, 3]

D2, 3

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets or curly braces instead of parentheses.

Passing arguments without parentheses.

Functions are called with parentheses and arguments inside, separated by commas.

3fill in blank

hard

Fix the error in the recursive function call to avoid infinite recursion.

Javascript

function countdown(n) {
  if (n <= 0) {
    console.log('Done');
    return;
  }
  console.log(n);
  countdown[1];
}

Drag options to blanks, or click blank then click option'

A(n - 1)

B(n + 1)

Cn - 1

Dn + 1

Attempts:

3 left

💡 Hint

Common Mistakes

Calling with n + 1 causing infinite recursion.

Forgetting parentheses around the argument.

To count down, the function must call itself with n - 1 inside parentheses.

4fill in blank

hard

Fill both blanks to create a function that returns the sum of squares of numbers in an array.

Javascript

function sumSquares(arr) {
  return arr.reduce((acc, num) => acc [1] num[2] 2, 0);
}

Drag options to blanks, or click blank then click option'

A+

B*

C**

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication instead of addition in reduce.

Using wrong operator for squaring.

The reduce function adds (+) the square (** 2) of each number.

5fill in blank

hard

Fill all three blanks to create a recursive function that calculates factorial of n.

Javascript

function factorial([1]) {
  if ([2] <= 1) {
    return 1;
  }
  return [3] * factorial(n - 1);
}

Drag options to blanks, or click blank then click option'

An

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names causing errors.

Missing base case or wrong condition.

The function uses n as parameter, checks if n <= 1, and returns n * factorial(n - 1).