What is TypeScript?

TypeScript is a superset of JavaScript that adds static types to JavaScript.

1
For static type checking code is analyzed by IDE at the time of writing the code.
2
it is a development tool and compiles into plain JavaScript.
3
It does not change the runtime behaviour of JavaScript code.
4
Once TypeScript’s compiler is done with checking your code, it erases the types to produce the resulting “compiled” code.
5
This means that once your code is compiled, the resulting plain JS code has no type information.