Build Your First TypeScript File

Video Lecture

Basic JavaScript File

Create yourself working a folder somewhere on your system.

mkdir tsbeginners

CD into it.

cd tsbeginners

And open VSCode

code .

In VSCode, create a new file called foo.js

const foo = (bar) => {
  return 'Hello, ' + bar
}

const baz = 'ABC'

console.log(foo(baz))

We can run this file directly in Nodejs or include it in a web page, and it will run inside the browser. But this isn't typescript.

Test it,

node foo.js

The TypeScript Equivalent

Rename the foo.js to foo.ts

const foo = (bar) => {
  return 'Hello, ' + bar
}

const baz = 'ABC'

console.log(foo(baz))

We can then compile it

tsc.cmd foo.ts

And then we can run it using Node.

node foo.js

The output will be

Hello, ABC

That is your very first typescript file.

Useful Links

ECMAScript Editions

https://www.w3schools.com/js/js_versions.asp

Metasyntactic Variables

I use metasyntactic variable names in this crash course.

Examples are foobar, foo, bar, baz, qux, quux, quuz, corge, grault, garply, waldo, fred, plugh, xyzzy, and thud.

They don't mean anything special, they are just good for using in code examples.

https://en.wikipedia.org/wiki/Metasyntactic_variable

https://www.typescriptlang.org/docs/handbook/compiler-options.html