Practice Questions

1. Asynchronous JavaScript (Callbacks, Promises, Async/Await)

• Write a function greetUser(name, callback) that prints a greeting and then calls the callback function.

• Create a promise that resolves after 3 seconds with a message "Data loaded successfully". Handle it using .then() and .catch().

• Rewrite the same promise using async/await and print the result.

2. APIs & Fetch

• Use fetch() to get data from https://jsonplaceholder.typicode.com/posts and display titles of first 5 posts in console.

• Handle errors using try…catch while fetching data.

3. Classes & Objects

• Create a class Car with properties brand and model and a method displayInfo(). Create 2 objects of this class and call the method for both.

• Extend the Car class with a subclass ElectricCar that adds a property batteryLife. Demonstrate inheritance.

4. Error Handling

• Write a function divide(a, b) that throws an error if b is zero. Handle it using try…catch.

• Create a form validation script that throws an error if input fields are empty.

5. Modules & Import/Export

• Create a module mathUtils.js that exports functions add(a,b) and multiply(a,b). Import them in another file and use them.

6. Advanced ES6+ Features

• Use array destructuring to extract first two elements from [10, 20, 30, 40].

• Use object destructuring to extract name and age from {name: "Raman", age: 25, city: "Delhi"}.

• Use spread operator to merge two arrays [1,2] and [3,4].

• Use rest operator in a function sum(...numbers) to add all numbers passed as arguments.

• Use optional chaining to safely access a nested property user.address.city when address may not exist.

✅ Summary:

• Practice covers asynchronous JavaScript, API calls, classes, error handling, modules, and modern ES6 features.

• Students should write, run, and debug code to understand each concept deeply.

• Prepares students for real-world web development scenarios.