Return inside loops in Javascript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return the first even number from the array.

Javascript

function firstEven(numbers) {
  for (let num of numbers) {
    if (num % 2 === 0) {
      return [1];
    }
  }
  return null;
}

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

Anumbers[0]

Bnumbers

Cnum % 2

Dnum

Attempts:

3 left

💡 Hint

Common Mistakes

Returning the whole array instead of the current number.

Returning an expression instead of the number.

Returning a fixed element like numbers[0] regardless of condition.

We return the current number 'num' when it is even.

2fill in blank

medium

Complete the code to return the index of the first negative number in the array.

Javascript

function firstNegativeIndex(arr) {
  for (let i = 0; i < arr.length; i++) {
    if (arr[i] < 0) {
      return [1];
    }
  }
  return -1;
}

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

Aarr[i]

B-1

Ci

Darr

Attempts:

3 left

💡 Hint

Common Mistakes

Returning the value instead of the index.

Returning the whole array.

Returning -1 inside the loop.

We return the index 'i' where the first negative number is found.

3fill in blank

hard

Fix the error in the code to return the first string longer than 3 characters.

Javascript

function firstLongString(strings) {
  for (const str of strings) {
    if (str.length > 3) {
      return [1];
    }
  }
  return null;
}

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

Astr.length

Bstr

Cstrings

Dstrings[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Returning the length instead of the string.

Returning the whole array.

Returning a fixed element regardless of condition.

Return the string 'str' that meets the length condition.

4fill in blank

hard

Fill both blanks to return the first number divisible by 5 and greater than 10.

Javascript

function findNumber(nums) {
  for (let [1] = 0; [2] < nums.length; [1]++) {
    if (nums[[1]] % 5 === 0 && nums[[1]] > 10) {
      return nums[[1]];
    }
  }
  return null;
}

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

Ai

Bj

Cnums.length

Dlength

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variables for loop index and condition.

Using 'length' without the array name.

Using 'j' in one place and 'i' in another.

Use 'i' as the loop variable and 'nums.length' as the loop limit.

5fill in blank

hard

Fill all three blanks to return the first word starting with 'a' and longer than 2 characters.

Javascript

function findWord(words) {
  for (let [1] = 0; [1] < words.length; [1]++) {
    let word = words[[1]];
    if (word.startsWith([2]) && word.length > [3]) {
      return word;
    }
  }
  return null;
}

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

Ai

B'a'

C2

D'A'

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase 'A' instead of lowercase 'a'.

Using wrong loop variable name.

Comparing length with wrong number.

Use 'i' as index, check startsWith('a'), and length > 2.