# Arrays & Tuples — TypeScript

Source: https://www.geekswithgeeks.com/en/typescript/ts-arrays-tuples

> Typed lists, and fixed-length, fixed-type tuples.

## Typed arrays

`number[]` or `Array<number>` both mean "an array of numbers only".

```typescript
let scores: number[] = [90, 85, 76];
let names: Array<string> = ["Ada", "Bo"];
scores.push("100");
// Error: Argument of type 'string' is not assignable to parameter of type 'number'.
```

## Tuples: fixed shape

A **tuple** is an array with a known length and a known type at each position.

```typescript
let point: [number, number] = [10, 20];
let entry: [string, number] = ["age", 36];
entry = [36, "age"];
// Error: Type 'number' is not assignable to type 'string'.
```

## Array vs tuple

Use an array for a variable-length list of the same kind of thing; use a tuple when position carries meaning, like `[key, value]`.