TypeScript is an open source language and is a superset of JS.

• offers additional features to js including static types.
• using types is completely optional
• compiles down to regular js
• can be used for FE js as well as BE with node.js
• includes most features from es6, es7 (classes, arrow function, etc)
• types from 3rd party libs can be added with type definitions

Dynamic vs Static typing

• Dynamically typed languages, the types are associated with run-time values and not named explicitly in your code ex) js, python, php, ruby
• Statically typed languages, you explicitly assign types to variables, function parameters, return values, etc ex) java, c, c++, rust, go

⇒ TypeScript is a static typed language.

In dynamically typed languages all type checks are performed in a runtime, only when your program is executing. So this means you can just assign anything you want to the variable and it will work.

If we take a look at Typescript, it is a statically typed language, so all checks will be performed during compile/build run before we actually execute our program.

Pros and Cons

Pros

• more robust
• easily spot bugs