Accessing array elements in Javascript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to access the first element of the array.

Javascript

const fruits = ['apple', 'banana', 'cherry'];
console.log(fruits[[1]]);

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

A0

B1

C2

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of 0 to access the first element.

Using an index that is out of range.

Arrays in JavaScript start at index 0, so the first element is at index 0.

2fill in blank

medium

Complete the code to access the last element of the array.

Javascript

const colors = ['red', 'green', 'blue', 'yellow'];
console.log(colors[colors.length [1] 1]);

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A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Adding 1 instead of subtracting 1 from length.

Using length directly as index.

To get the last element, subtract 1 from the array's length because indexes start at 0.

3fill in blank

hard

Fix the error in the code to correctly access the second element.

Javascript

const numbers = [10, 20, 30, 40];
console.log(numbers[[1]]);

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A1

B2

C0

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 2 to access the second element.

Using index 0 which is the first element.

The second element is at index 1 because counting starts at zero.

4fill in blank

hard

Fill both blanks to create an array of squares for numbers greater than 2.

Javascript

const numbers = [1, 2, 3, 4, 5];
const squares = numbers.filter(n => n [1] 2).map(n => n [2] n);
console.log(squares);

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

A>

B<

C**

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in filter.

Using '**' which is exponentiation but less common in JS for this task.

Filter numbers greater than 2, then multiply each number by itself to get squares.

5fill in blank

hard

Fill all three blanks to create an object mapping each fruit to its length if length is greater than 5.

Javascript

const fruits = ['apple', 'banana', 'cherry', 'date'];
const result = {};
for (let [1] of fruits) {
  if ([1].length > 5) {
    result[[1]] = [2];
  }
}
console.log(result);

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

Afruit

Bfruit.length

Cfor

Dof

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'for ... in' instead of 'for ... of'.

Using fruit instead of fruit.length for the value.

This uses a for...of loop to iterate over the array and build an object mapping fruit names to their lengths if the length is greater than 5. BLANK_1 is the loop variable name, BLANK_2 is the value (length), and BLANK_3 is the loop keyword for.