A practical, easy-to-follow guide from JavaScript to TypeScript

These notes follow the topics in the uploaded TypeScript Full Course

PDF. I've rewritten the explanations in a more natural, student-friendly

way and kept the examples close to the original material.

1. What is TypeScript?

TypeScript is JavaScript with an extra layer of type checking.

In JavaScript, a variable can hold different kinds of values as your

program runs. That flexibility is useful, but it can also lead to

mistakes that are difficult to spot.

TypeScript lets us describe what kind of value a variable should

contain. It checks those rules while we are writing and compiling the

code.

One important thing to remember: TypeScript does not run directly in

the browser or Node.js. It is compiled into JavaScript first.…