# Why TypeScript? — TypeScript

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

> A superset of JavaScript that adds static types.

## What TypeScript adds

TypeScript is JavaScript **plus static types**. Every valid JS file is already valid TS — you opt into type checking gradually, and errors surface while you type, not in production.

## A spellchecker for code

Plain JS runs your sentence even with a typo and fails later. TypeScript is a **spellchecker** — it underlines the mistake before you hit "send".

## Caught before running

In plain JS this typo runs and silently returns `undefined`. TS refuses to compile it.

```typescript
function greet(name: string) {
  return `Hello, ${nmae}!`; // typo: 'nmae'
}
// Error: Cannot find name 'nmae'. Did you mean 'name'?
```