Course/Module 2/Topic 3 of 3Beginner

Type Annotations & Inference - Practice

Put your type annotations & inference skills to the test with practical exercises and challenges.

50 min•By Priygop Team•Last updated: Feb 2026

Hands-On Practice

Practice makes perfect! In this section, you'll work through practical exercises that reinforce the concepts covered in this module.

Exercises

Exercise 1: Apply basic type annotations & inference concepts
Exercise 2: Solve intermediate-level challenges
Exercise 3: Build a mini-project using type annotations & inference
Exercise 4: Debug and fix common issues

Practice: Type Annotations & Inference

Practice: Type Annotations & InferenceJavaScript⚠ 1 error

⚠ Syntax Issues (1)

Line 1: JS Error: Unexpected token ':'

💡 Missing or extra {}()[] or operator near the error.

JavaScript Editor

✕ 1 errorTab = 2 spaces

// Try changing types and see errors!
let name: string = "Your Name";
let age: number = 25;
let hobbies: string[] = ["coding", "reading"];

// Union type
let result: string | number = "success";
result = 200; // This works!
// result = true; // This would cause an error!

console.log(`${name} is ${age} years old`);
console.log("Hobbies:", hobbies.join(", "));

Result

Click ▶ Run to see the result

Edit the code on the left, then click Run

JavaScript|12 lines|361 chars|1 error, 0 warnings

UTF-8

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