Why typed arrays matter in Typescript - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a typed array of numbers.

Typescript

let numbers: [1] = [1, 2, 3, 4];

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Anumber[]

Bstring[]

Cany[]

Dboolean[]

Attempts:

3 left

💡 Hint

Common Mistakes

Using string[] instead of number[] causes type errors.

Using any[] loses the benefit of type safety.

Typed arrays specify the type of elements they hold. Here, number[] means an array of numbers.

2fill in blank

medium

Complete the code to declare a typed array of strings.

Typescript

const fruits: [1] = ['apple', 'banana', 'cherry'];

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Aboolean[]

Bstring[]

Cnumber[]

Dany[]

Attempts:

3 left

💡 Hint

Common Mistakes

Using number[] for string elements causes errors.

Using any[] removes type checking benefits.

The array holds strings, so the type string[] is correct.

3fill in blank

hard

Fix the error in the typed array declaration.

Typescript

let flags: [1] = [true, false, true];

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Astring[]

Bnumber[]

Cboolean[]

Dany[]

Attempts:

3 left

💡 Hint

Common Mistakes

Using string[] or number[] causes type mismatch errors.

Using any[] works but loses type safety.

The array contains boolean values, so the type must be boolean[].

4fill in blank

hard

Fill both blanks to declare a typed array and add a new element.

Typescript

let scores: [1] = [10, 20, 30];
scores.[2](40);

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Anumber[]

Bpush

Cpop

Dstring[]

Attempts:

3 left

💡 Hint

Common Mistakes

Using string[] for numbers causes errors.

Using pop removes elements instead of adding.

The array holds numbers, so number[] is correct. To add an element, use the push method.

5fill in blank

hard

Fill all three blanks to declare a typed array, add an element, and access an element.

Typescript

let names: [1] = ['Alice', 'Bob'];
names.[2]('Carol');
const first: [3] = names[0];

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

Astring[]

Bpush

Cstring

Dnumber[]

Attempts:

3 left

💡 Hint

Common Mistakes

Using number[] for string arrays causes errors.

Using pop instead of push removes elements.

Using number type for accessed element causes type mismatch.

The array holds strings, so string[] is correct. Use push to add an element. Accessing an element returns a string.