TypeScript is fun!

TypeScript improves the development experience of JavaScript in two ways.

First, at its most basic, TypeScript is about adding _documentation_ on top of JavaScript. And if you configure your project correctly, it can force you to do so. And of course not just yourself, but any other developers working on a project. And that documentation is partial — it doesn’t intend to cover all the information documentation should provide. But it does provide one very specific information: and that is the type of information a variable should contain.

JavaScript will happily return true to the statement number zero equals the empty string. But strings and numbers are two different things. They are two different types. JavaScript is weakly typed or even untyped. In JavaScript, you can assign a value of any type to any variable at any time.

TypeScript adds type to coding in JavaScript. (There is a clue in the name).

That type-checking is only done at compilation time, not once the code is being run. That type-checking complains if you’ve said a variable a certain type and then use it differently. This means TypeScript makes you a (slightly) better coder. It also makes your development tools better development tools: adding constraints helps your tools better guess what you are trying to do and therefore help you get there faster.

And faster is nice. As is better.

Gao, Bird, and Barr examined how type annotations can detect bugs in JavaScript, and found a . Having worked for over 15 years with a lot of loosely typed languages (most notably LUA, Python, and JavaScript) I would say 15% feels like an underestimation.

The second way TypeScript removes the hassle and makes things more fun, is that it anticipates future JavaScript syntax, and allows you to target past JavaScript syntax. JavaScript has improved a lot over the years, but when I started using it, there was no fat arrow, no promises, and no spread operator. Those were in the works, of course, but couldn’t be used because the browsers didn’t support them.

And TypeScript allowed me to use the nicer, cleaner syntax without worrying about compatibility because I could transpile the code back to the old syntax, and choose the level of compatibility I wanted the TypeScript compiler to output.

And that is nice and refreshing when you’ve spent any amount of time battling JavaScript compatibility issues.

Of course, things have improved now because those funky new features have made their way into JavaScript. But someday, a new shiny feature will be proposed for the JavaScript language… and TypeScript will have it first.

Because TypeScript necessarily moves faster than JavaScript adoption. And that is also part of what makes TypeScript a good choice to learn.