Is unit testing required in TypeScript?

People say unit testing is important.
I'm a development junior with no unit testing.
I'm using TypeScript.
Typescript checks all the results from the function.
Do I need unit tests in this case?

I want to try a test library called Jest.
But i don't know what is necessary in my case.
I am using a development environment using React and Apollo
I think typescript is enough.

Do I really need unit tests? Please provide an example if needed.