Understanding TypeScript Types: Basics and Examples

TypeScript has revolutionized the way we write JavaScript by introducing a powerful type system. As a developer who’s spent countless hours debugging JavaScript code, I can’t emphasize enough how TypeScript has made my life easier. Let’s dive into the fundamental types that make TypeScript so valuable.

The Building Blocks: Basic Types

When I first started with TypeScript, understanding the basic types was my foundation. These are the simplest yet most crucial elements you’ll work with:

Number

In TypeScript, all numbers, whether integers or decimals, are represented by the number type. Here’s how I use them in my daily coding:

let price: number = 99.99;
let quantity: number = 42;
let temperature: number = -5;

String

Strings are probably the most commonly used type in any programming language. In TypeScript, we can be explicit about our string declarations:

let firstName: string = "John";
let message: string = `Hello, ${firstName}`;

Boolean

The boolean type might seem simple, but it’s incredible how much clearer your code becomes when you explicitly declare boolean variables:

let isActive: boolean = true;
let isLoggedIn: boolean = false;

Working with Arrays and Tuples

Arrays are where TypeScript really starts to shine. I remember how many bugs I used to encounter with JavaScript arrays - TypeScript makes those a thing of the past:

let numbers: number[] = [1, 2, 3, 4, 5];
let fruits: Array<string> = ["apple", "banana", "orange"];

The Power of Custom Types

One of my favorite features in TypeScript is the ability to create custom types. It’s like having a blueprint for your data:

type User = {
  id: number;
  name: string;
  email: string;
  isAdmin: boolean;
};

let currentUser: User = {
  id: 1,
  name: "John Doe",
  email: "john@example.com",
  isAdmin: false
};

Union Types: Flexibility When You Need It

Sometimes we need variables that can hold different types of values. Union types are TypeScript’s elegant solution to this:

let statusCode: number | string = 200;
statusCode = "OK"; // This is also valid

Remember, TypeScript’s type system is your friend. It might feel like extra work at first, but trust me - the peace of mind and productivity boost you get from catching errors at compile-time instead of runtime is absolutely worth it.

Conclusion

As you continue your TypeScript journey, you’ll discover that these basic types are just the beginning. The type system is incredibly rich and flexible, allowing you to express complex relationships between data in your applications. Start with these fundamentals, and you’ll be well on your way to writing more reliable and maintainable code.