TypeScript Simple Types

TypeScript tutorial

🧩 TypeScript Simple Types

TypeScript Simple Types are the basic data types used to define what kind of value a variable can hold.

They help prevent errors and make code more readable.

1️⃣ number

Used for integers and floating-point numbers.

let age: number = 25;
let price: number = 99.99;

2️⃣ string

Used for text values.

let name: string = "Sanjit";
let message: string = Welcome ${name};

3️⃣ boolean

Used for true / false values.

let isLoggedIn: boolean = true;
let hasAccess: boolean = false;

4️⃣ any

Allows any type of value (avoid using when possible).

let data: any = 10;
data = "Hello";
data = true;

📌 Use any only when you don’t know the type.

5️⃣ unknown (Safer than any)

Requires type checking before use.

let value: unknown = "TypeScript";

if (typeof value === “string”) {
console.log(value.toUpperCase());
}

6️⃣ null and undefined

Used for empty or missing values.

let result: null = null;
let notAssigned: undefined = undefined;

With strictNullChecks:

let value: string | null = null;

7️⃣ array

Used to store multiple values of the same type.

let numbers: number[] = [1, 2, 3];
let fruits: Array<string> = ["Apple", "Banana"];

8️⃣ tuple

Array with fixed number and type of elements.

let user: [number, string] = [1, "Sanjit"];

9️⃣ enum

Defines a set of named constants.

enum Direction {
Up,
Down,
Left,
Right
}let move: Direction = Direction.Up;

🔟 void

Used when a function returns nothing.

function greet(): void {
console.log("Hello TypeScript");
}

1️⃣1️⃣ never

Used when a function never returns.

function throwError(): never {
throw new Error("Something went wrong");
}

📌 Type Inference

TypeScript can automatically detect types.

let count = 10; // TypeScript infers number

🔍 Simple Types Summary

Type Purpose
number Numeric values
string Text
boolean true/false
any Any type
unknown Safe any
null Empty
undefined Not assigned
array List of values
tuple Fixed structure
enum Named constants
void No return
never Never returns

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