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Working with Collections

When building applications, we often need to work with collections of data. TypeScript provides two main ways to handle this: Arrays and Objects.

Arrays: Ordered Lists​

Arrays are like a line of items, where each item has its position. Think of them as a shopping list or a playlist.

// An array of numbers (like scores in a game)
let scores: number[] = [85, 92, 78, 95];

// An array of strings (like a list of player names)
let players: string[] = ["Alex", "Sam", "Taylor"];

You can also write arrays using a different syntax:

let scores: Array<number> = [85, 92, 78, 95];

Objects help us group related information together. They're perfect for representing things with multiple properties.

// Describing a player in a game
type Player = {
    name: string;
    score: number;
    isActive: boolean;
}

let player1: Player = {
    name: "Alex",
    score: 85,
    isActive: true
};

Combining Arrays and Objects​

Often, you'll work with arrays of objects. This is very common in real applications:

let players: Player[] = [
    { name: "Alex", score: 85, isActive: true },
    { name: "Sam", score: 92, isActive: false },
    { name: "Taylor", score: 78, isActive: true }
];

Best Practices​

  1. Always define object shapes using interfaces or types
  2. Use consistent naming conventions
  3. Consider making properties optional when appropriate: 
    type Player = {
        name: string;
        score: number;
        isActive: boolean;
        lastLogin?: Date;  // Optional property
    }

Practice Exercise​

Try creating an array of objects representing your favorite books. Include properties like title, author, and year published.