TypeScript Basics

This is a repository that demonstrates basic concepts of TypeScript, a strongly typed programming language. The example code introduces how to define strict types, use types throughout code, work with union types, arrays, objects, functions, type aliases, interfaces, and generics.

Strict Types

In TypeScript, it is a practice to define strict types and use them consistently throughout your code. This helps avoid type errors.

let variable: string = "hello";: Defines a variable with a strict type.
let age: number = 19;: Example of a strict numeric variable.
let testString: string; and let testBoolean: boolean;: Declaration of variables without assigning an initial value.

Types of Union

Union types allow a variable to have more than one possible type.

let testStringOrNumber: string | number;: Example of a variable that can be a string or a number.

Arrays

Arrays can contain values of the same type.

let names: string[] = ["Melvin", "Messias", "Tivane"];: Example of an array of strings.
let numbers: number[] = [11, 22, 33];: Example of an array of numbers.

Objects

Objects can have properties with strict types.

let user = { username: "john", age: 22, isAdmin: false };: Example of an object with typed properties.
let userObject: { username: string; age: number; isAdmin: boolean; }: Strict definition of an object type.

Any type

The any type is used when the exact type is not known.

let testAny: any;: Example of a variable with type any.

Functions

Functions can have strict types for arguments and returns.

let sayHi = (): void => { console.log("Hi, welcome!"); }: Example of a non-return function.
let functionReturnString = (): string => { return "Hello"; }: Function that returns a string.
let multiple = (number: number): number => { return number * 2; }: Function that accepts and returns numbers.

Type Aliases

Type aliases allow you to create custom names for types.

type UserType = { username: string; age: number; phone: string; }: Example of a type alias.

Interfaces

Interfaces define the structure of objects.

interface IUser { username: string; email: string; age: number; }: Example of an interface.
interface IEmployee extends IUser { employeeId: number; }: Interface inheritance.

Generics

Generics allow you to create types that can be reused with different types.

interface IPostBetter<T> { id: number; title: string; desc: string; extra: T[] }: Example of a generic interface.

Usage

This example code demonstrates basic TypeScript concepts. Use it as a reference to understand how to work with types, functions, objects, and more in TypeScript.

Contribution

Feel free to contribute improvements, bug fixes or add more examples. Open an issue or submit a pull request with your changes.

melvintivane / typescript-getting-started