In the previous tutorial, we learned about type narrowing and type guards. Now let’s learn about generics — one of the most powerful features in TypeScript. By the end of this tutorial, you will know how to write generic functions, interfaces, and constraints. You will also learn common patterns like keyof, default type parameters, and generic utility functions. Why Generics? Imagine you need a function that returns the first element of any array: ...
In the previous tutorial, we learned about enums and const assertions. Now let’s learn about type narrowing — one of the most important concepts in TypeScript. By the end of this tutorial, you will know how to use typeof, instanceof, custom type guards, discriminated unions with switch, and exhaustive checking with never. What is Type Narrowing? Type narrowing means making a type more specific within a block of code. When you have a union type like string | number, TypeScript can figure out the exact type based on your checks. ...
In the previous tutorial, we learned about union types and literal types. Now let’s learn about enums and const assertions — two ways to define a fixed set of values in TypeScript. By the end of this tutorial, you will know when to use enums, when to use as const, and how the satisfies operator works. What is an Enum? An enum (enumeration) is a way to define a group of named constants. TypeScript has three kinds: numeric enums, string enums, and const enums. ...
In the previous tutorial, we learned about objects and interfaces. Now let’s learn about union types, literal types, and type aliases — patterns that make TypeScript truly powerful. By the end of this tutorial, you will know how to use union types, literal types, discriminated unions, intersection types, and type aliases. Union Types A union type means “this value can be one of several types.” Use the | (pipe) symbol: let id: string | number; id = "abc-123"; // OK — string id = 42; // OK — number id = true; // Error: Type 'boolean' is not assignable to type 'string | number' Union types are everywhere in real code. A function that accepts multiple types: ...
In the previous tutorial, we learned how to type functions. Now let’s learn how to describe the shape of objects — one of the most important skills in TypeScript. By the end of this tutorial, you will know how to define object types, use interfaces, extend them, and choose between interfaces and type aliases. Object Types You can describe an object’s shape by listing its properties and types: let user: { name: string; age: number } = { name: "Alex", age: 25, }; TypeScript checks that the object matches the shape: ...
In the previous tutorial, we learned the basic types in TypeScript. Now let’s learn how to use types with functions — the building blocks of every program. By the end of this tutorial, you will know how to type every kind of function in TypeScript. Function Parameter Types In TypeScript, you must add types to function parameters. TypeScript cannot infer parameter types: // JavaScript — no types function greet(name) { return "Hello, " + name; } // TypeScript — types required function greet(name: string) { return "Hello, " + name; } If you forget to add a type, TypeScript gives an error with strict: true: ...
In the previous tutorial, we installed TypeScript and wrote our first program. Now let’s learn the type system — the core feature that makes TypeScript useful. By the end of this tutorial, you will know every basic type in TypeScript and when to use each one. Type Annotations A type annotation tells TypeScript what type a variable should be. You add it after the variable name with a colon: let name: string = "Alex"; let age: number = 25; let isActive: boolean = true; The : string, : number, and : boolean are type annotations. If you try to assign the wrong type, TypeScript gives an error: ...
In the previous tutorial, we learned what TypeScript is and why it matters. Now let’s install it and write our first program. By the end of this tutorial, you will have TypeScript installed, VS Code configured, and a working project you built yourself. Step 1: Install Node.js TypeScript runs on Node.js. If you don’t have Node.js installed, download the LTS version from nodejs.org. After installation, verify it works: node --version # v22.x.x or later npm --version # 10.x.x or later If both commands print version numbers, you are ready. ...
TypeScript is everywhere. It became the #1 most-used language on GitHub in August 2025, surpassing Python. It now ranks among the top languages in every major developer survey. If you write JavaScript, TypeScript is no longer optional — it is expected. This tutorial series will take you from zero to confident TypeScript developer. We start here: what TypeScript actually is, and why you should learn it in 2026. What is TypeScript? TypeScript is a superset of JavaScript that adds static types. Every valid JavaScript file is already valid TypeScript. TypeScript just adds extra features on top. ...
Python is the most popular programming language in the world right now. It has been the number one language on the TIOBE Index since 2021 and holds a record-breaking 26% rating in 2025-2026. But why? What makes Python so popular? And should you learn it? In this tutorial, we will answer these questions. By the end, you will understand what Python is, where it is used, and why it is worth learning in 2026. ...