This tutorial continues our TypeScript beginner series, building upon previous introductions to TypeScript features, installation, and IDE suggestions. The second tutorial covered TypeScript data types and their error-prevention benefits.

This part focuses on interfaces. We'll explore how interfaces, like x and Point (with width), and Cuboid (extending Point with length and height), help define object structures. The Cuboid example demonstrates specifying values for all properties and using a function to calculate volume.

It's crucial to note that interfaces are a TypeScript-specific feature, absent in JavaScript. Compiling the TypeScript code results in the following JavaScript equivalent:

function volumeCuboid(cuboid) {
    let volume = cuboid.length * cuboid.width * cuboid.height;
    console.log(`Volume: ${volume}`);
}

let cuboid = { x: -22, y: 28, width: 12, length: 32, height: 20 };

volumeCuboid(cuboid);
// Volume: 7680

The tutorial also touches upon intersection types, contrasting them with interface extension. We examine how to create a RoundedRectangle using existing types, highlighting the differences between merging multiple interface declarations (allowed) and redeclaring types (resulting in errors).

Key Takeaways:

This tutorial provides a foundation in TypeScript interfaces, emphasizing their role in writing robust code. You've learned to create interfaces with optional and read-only properties, and to utilize index signatures for adding dynamic properties beyond the initial interface definition. For deeper understanding, refer to the official TypeScript documentation.

The next tutorial will delve into TypeScript classes.