Describe a meeting room
Before you start this intermediate track
JavaScript objects and functions. The lessons introduce narrowing, unions, and optional properties.
Guided code reading and debugging. Runnable coding challenges are available in JavaScript, Python, and SQL.
Understand it, then try it.
An object type spells out the properties a value must provide and the type of each property. Here, Room requires a text name and a numeric capacity. Annotating room lets TypeScript check that shape before the code runs. The values remain ordinary JavaScript properties when the program builds its display label.
type Room = { name: string; capacity: number };const room: Room = { name: "Cedar", capacity: 6 };const label = `${room.name}: ${room.capacity} seats`;console.log(label);Use TypeScript 5+ with strict checking and an ES2020 target. Each mission is an independent file. Compile the TypeScript to JavaScript, then run it with Node.js or in a browser console.
Track the values line by line. Predict the result before running this example in your own editor.