Matt Steele

Every Java Developer Should Learn TypeScript

01 Nov 2017

I gave a talk to the Omaha Java Users Group about TypeScript:

I think there's a lot of things TypeScript has to offer Java developers, namely:

Static Typing - This one's obvious; if you're used to a compiler providing thousands of tiny continuously-running unit tests, you're going to miss that on the front-end.

But what's even cooler is TypeScript's features of incremental and inferred typing. You can achieve full type safety in this code:

class MathFns {
  static for(val) {
    return {
      square() {
        return val * val;
      }
    }
  }
}

const fns = MathFns.for(5);
console.log(fns.square());

By adding a single type token:

class MathFns {
  static for(val:number) {
    return {
      square() {
        return val * val;
      }
    }
  }
}

const fns = MathFns.for(5);
console.log(fns.square());

Inferred typing means you add drastically fewer tokens than you would to make Java code typesafe; conservatively you'd have to add least six type tokens in an equivalent Java program. Incremental typing means you can convert existing JavaScript code into TypeScript without it being all-or-nothing.

I also appreciate TypeScript's structural type system, which also provides strong type-safety without having to declare that a function implements a particular interface, or extends from a parent class, etc. This article goes deep into the differences.

It's also easy to integrate into a Java workflow, with Maven and Gradle plugins if you wanna use them, as well as tooling for Eclipse, IntelliJ, and other IDEs.

I'm still getting over the cognitive dissonance that a tool from Microsoft, created by the C# language designer, might be the best way to ease Java developers into the front-end. But now that I'm used to static typing, I get angry when I have to go back to vanilla JavaScript, and I have TypeScript to thank for that.

Regardless of what Rich Hickey says.