Scala.js
A safer way to build complex, bug-free
front-end web applications!
Correctness
Performance
Interoperability
Excellent editor support
With Scala.js, typos and type-errors are immediately caught and shown to you in your editor, without even needing to compile your code. Refactor any field or method with ease, with the confidence that if you mess it up the editor will tell you immediately. Stop flipping back and forth between your editor and MDN, because your editor will display what methods are available, what arguments they take, what they return, and even their documentation, right in-line with your code!
Go beyond JavaScript ES6, today
Classes
ECMAScript 6
class Person {
constructor(firstName) {
this.firstName = firstName;
}
walk() {
console.log("I am walking!");
}
sayHello(target) {
console.log(`Hello ${target}, I'm ${this.firstName}`);
}
}Scala.js
class Person(val firstName: String) {
def walk(): Unit = println("I am walking!")
def sayHello(target: String): Unit =
println(s"Hello $target, I'm $firstName")
}Fat arrow functions
ECMAScript 6
const names = persons.map(p => p.firstName);Scala.js
val names = persons.map(p => p.firstName)
// or an even shorter version
val names = persons.map(_.firstName)Collections
ECMAScript 6
const personMap = new Map([
[10, new Person("Roger Moore")],
[20, new Person("James Bond")]
]);
const names = [];
for (const [key, person] of personMap) {
if (key > 15) {
names.push(`${key} = ${person.firstName}`);
}
}Scala.js
val personMap = Map(
10 -> new Person("Roger Moore"),
20 -> new Person("James Bond")
)
val names = for {
(key, person) <- personMap
if key > 15
} yield s"$key = ${person.firstName}"To find out more about what Scala.js looks like for JavaScript developers, check out the detailed comparisons. If you want to try it out yourself, check out the Tutorials!
| Feature | JavaScript ES5 | JavaScript ES6 | TypeScript | Scala.js |
|---|---|---|---|---|
| Interoperability | ||||
| Fully EcmaScript5 compatible | ||||
| No compilation required | ||||
| Use existing JS libraries | ||||
| Language features | ||||
| Classes with inheritance | ||||
| Modules | ||||
| Support for types | ||||
| Strong type system | ||||
| Extensive system libraries | ||||
| Optimizing compiler | ||||
| Macros, to extend the language | ||||
| IDE support | ||||
| Catch most errors in IDE | ||||
| Easy and reliable refactoring | ||||
| Reliable code completion | ||||