Parameter type annotations in Typescript - Mini Project: Build & Apply

Parameter Type Annotations in TypeScript

📖 Scenario: You are building a simple calculator function that adds two numbers. To make your code clear and safe, you want to specify the types of the inputs.

🎯 Goal: Create a function called add that takes two numbers as parameters with type annotations and returns their sum.

📋 What You'll Learn

Create a function named add with two parameters: a and b.

Add type annotations to both parameters to specify they are numbers.

Return the sum of a and b.

Call the add function with arguments 5 and 7 and print the result.

💡 Why This Matters

🌍 Real World

Type annotations are used in real projects to make code easier to understand and safer by preventing wrong types from being used.

💼 Career

Many programming jobs require writing TypeScript with proper type annotations to maintain large codebases and reduce bugs.

1

Create the add function with parameters

Write a function called add that takes two parameters named a and b without type annotations yet.

Typescript

function add(a, b) {
  // Your code here
}

Need a hint?

Start by writing a function with two parameters. Don't add types yet.

2

Add type annotations to parameters

Modify the add function to add type annotations : number to both parameters a and b.

Typescript

function add(a: number, b: number) {
  return a + b;
  // Your code here
}

Need a hint?

Use : number after each parameter name to specify the type.

3

Call the add function with numbers

Call the add function with arguments 5 and 7 and store the result in a variable named result.

Typescript

function add(a: number, b: number) {
  return a + b;
}

const result = add(5, 7);
// Your code here

Need a hint?

Use const result = add(5, 7); to call the function and save the output.

4

Print the result

Write a console.log statement to print the value of the variable result.

Typescript

function add(a: number, b: number) {
  return a + b;
}

const result = add(5, 7);

console.log(result);
// Your code here

Need a hint?

Use console.log(result); to show the sum in the console.