Basic Types

Types describe what kind of data a variable holds.

Common basic types

• number
• string
• boolean
• any
• unknown

let age: number = 25;
let name: string = "Tom";
let active: boolean = true;

any (avoid if possible)

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

any removes safety.

unknown (safer than any)

let value: unknown = "text";

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

Arrays

let scores: number[] = [10, 20, 30];
let names: Array<string> = ["Tom", "Sarah"];

Tuple

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

Remember

• types explain intent
• avoid any
• use unknown when unsure