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TS Simple Types

TypeScript extends JavaScript with static typing for more reliable code. Let’s explore TypeScript’s simple (primitive) types, including string, number, boolean, and more.

Key Topics

Types Overview

In TypeScript, the primitive types include: string, number, boolean, null, undefined, and symbol. The bigint type is also available for large integers.

String Type

A string in TypeScript is a sequence of characters. TypeScript ensures that you use string-based operations on string variables.

let firstName: string = "Alice";
// firstName = 123; // Error: Type 'number' is not assignable to type 'string'.

console.log(`Hello, ${firstName}`);

Output

Hello, Alice

Number Type

The number type covers both integer and floating-point values. TypeScript also supports hex, octal, and binary literals.

let age: number = 30;
age = 31.5;
// age = "thirty"; // Error: Type 'string' is not assignable to type 'number'.

console.log(`Age is ${age}`);

Output

Age is 31.5

Boolean Type

A boolean type can only be true or false. It’s useful for representing binary states.

let isLoggedIn: boolean = false;

function loginUser() {
    isLoggedIn = true;
    console.log(`User login status: ${isLoggedIn}`);
}

loginUser();

Output

User login status: true

Key Takeaways

  • Primitive Types: TypeScript supports standard JavaScript types (string, number, boolean, etc.).
  • Static Checking: Assigning the wrong type results in compile-time errors.
  • Consistency: Types help maintain consistent and bug-free code.
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