# What is TypeScript ?
TypeScript is a programming language created by microsoft.
- built on top of JavaScipt It addresses shortcomings of Vanilla JavaScipt.
So, everything you can do in JS - you also can do in TS.
You can think of it like a bubble.
# TypeScript Features
Some features TypeScript supports, that JS does not.
- Static typing (number, string, …)
- TS compiler - at compiletime
- code completion
- refactoring
- shorthand notations
# TypeScript Drawbacks
- Compilation - “Transpilation” - browser translates .ts into .js
- Discipline in coding
# Additional Types
There are some additional types, that vanialla JS does not support. Look at 00_TS_DataTypes.
| JavaScript | TypeScript |
|---|---|
| number | any |
| string | unknown |
| boolean | never |
| null | enum |
| undefined | tuple |
| object |
Note: in TypeScript, you don’t even need to define a variable with its type.
// The compiler already knows, that it's a number
let sales = 123;
// The compiler says the same with this one
let sales2: number = 234;