Why typed arrays matter in Typescript - Challenge Your Understanding

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of Typed Array Initialization

What is the output of this TypeScript code snippet using a typed array?

Typescript

const arr = new Uint8Array([10, 20, 300]);
console.log(arr);

A Uint8Array(3) [10, 20, 300]

B TypeError: Invalid value in typed array

C Uint8Array(3) [10, 20, 44]

D Uint8Array(3) [10, 20, 0]

💡 Hint

Remember that Uint8Array stores values as 8-bit unsigned integers, so values above 255 wrap around.

Uint8Array stores numbers between 0 and 255. The value 300 wraps around modulo 256, so 300 % 256 = 44.

🧠 Conceptual

intermediate

Why Use Typed Arrays Instead of Normal Arrays?

Which of the following is the main reason to use typed arrays like Uint16Array over normal JavaScript arrays?

A Typed arrays provide fixed-size, efficient storage of binary data with consistent element types.

B Typed arrays automatically resize when elements are added or removed.

C Typed arrays allow storing any type of data including objects and strings.

D Typed arrays can store negative and positive numbers without limits.

💡 Hint

Think about performance and memory when working with binary data.

Typed arrays provide fixed-size buffers with elements of a single type, making them efficient for binary data and interfacing with low-level APIs.

🔧 Debug

advanced

Debug Typed Array Element Assignment

What error or output will this TypeScript code produce?

Typescript

const buffer = new ArrayBuffer(4);
const view = new Uint16Array(buffer);
view[0] = 65536;
console.log(view[0]);

A 65536

B 0

C RangeError: Value out of range

D undefined

💡 Hint

Consider the size limit of Uint16Array elements and how values are stored.

Uint16Array elements store 16-bit unsigned integers (0 to 65535). Assigning 65536 wraps around to 0 because 65536 % 65536 = 0.

📝 Syntax

advanced

Identify Syntax Error in Typed Array Declaration

Which option contains a syntax error when declaring a typed array in TypeScript?

A const arr = new Uint8Array{10, 20, 30};

B const arr = new Int8Array(5);

C const arr = new Uint16Array(new ArrayBuffer(4));

D const arr = new Float32Array([1.5, 2.5, 3.5]);

💡 Hint

Check the brackets used for array initialization.

Typed arrays must be initialized with parentheses and either an array or a length. Curly braces {} are invalid syntax here.

🚀 Application

expert

Calculate Sum of Elements in a Typed Array

Given the following TypeScript code, what is the value of sum after execution?

Typescript

const data = new Int8Array([-128, 127, 1, -1]);
let sum = 0;
for (const num of data) {
  sum += num;
}
console.log(sum);

A 255

B TypeError: Cannot iterate over Int8Array

C 0

D -1

💡 Hint

Add the numbers carefully considering their signed 8-bit values.

Sum is (-128) + 127 + 1 + (-1) = -1.