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TypeScript · BeginnerSnippet

Simple Interfaces

Interfaces are used to describe the shape of an object. They act as a contract for what properties an object should have.

snippet.ts

typescript

interface User {
  id: number;
  username: string;
}
 
const user: User = {
  id: 1,
  username: "alex"
};

SyntaxBest Practices

TypeScript · BeginnerSnippet

Type Annotations

Type annotations allow us to explicitly specify the type of a variable. This helps the compiler catch errors if we try to assign a value of the wrong type.

snippet.ts

typescript

let count: number = 10;
let message: string = "Hello TypeScript";
let isActive: boolean = true;

SyntaxData Types

TypeScript · BeginnerSnippet

Basic Function Types

In TypeScript, you can define the types of the parameters a function receives and the type of the value it returns.

snippet.ts

typescript

function greet(name: string): string {
  return "Hello, " + name;
}

FunctionsSyntax

TypeScript · BeginnerSnippet

Defining Arrays

TypeScript allows you to define arrays that contain only a specific type of element, preventing accidental mixed-type arrays.

snippet.ts

typescript

const fruits: string[] = ["Apple", "Banana"];
const scores: Array<number> = [95, 88, 100];

Arrays & ListsData Types

TypeScript · BeginnerSnippet

Union Types

Union types allow a variable to be one of several types. This is useful when a value could legitimately be different types.

snippet.ts

typescript

let result: string | number;
result = "Success";
result = 200;

Data TypesSyntax

TypeScript · BeginnerSnippet

Optional Chaining

The optional chaining operator (?.) permits reading the value of a property deep within a chain of objects without having to check if each reference is valid.

snippet.ts

typescript

const user = { details: { name: 'Bob' } };
const name = user?.details?.name;

SyntaxBest Practices

TypeScript · BeginnerSnippet

Nullish Coalescing

The nullish coalescing operator (??) returns its right-hand operand when its left-hand operand is null or undefined. Unlike ||, it treats 0 as a valid value.

snippet.ts

typescript

const settings = { volume: 0 };
const volume = settings.volume ?? 50;

SyntaxControl Flow

TypeScript · BeginnerSnippet

Type Assertions

Type assertions are a way to tell the compiler to treat a value as a specific type when you have more information about it than TypeScript does.

snippet.ts

typescript

const rawData: any = '123';
const dataLength = (rawData as string).length;

Syntax