Eclipse N4JS Language and IDE
High-quality JavaScript development
for large Node.js projects

N4JS is for Java and JavaScript Developers

  • You are a Java developer and missing the comfort of familiar tools while developing for JavaScript environments?
  • You are a JavaScript developer and want to write large-scale server-side applications in a way that it stays maintainable?
  • You are a TypeScript developer and ran into problems the type checker didn't catch?

N4JS is a general-purpose programming language based on ECMAScript. It adds a static type system as reliable as that of Java, but with the flexibility of JavaScript. The language provides built-in support for state-of-the-art programming paradigms such as dependency injection and test support. Code is validated as you type with the addition of tools such as content-assist and quick-fixes which ensure your code is written safely and intuitively. N4JS transpiles to ECMAScript code, using features supported by Node.js. Based on the Language Server Protocol, the N4JS language server can be integrated into several LSP clients. For VSCode we provide an extension for N4JS via the VSCode marketplace.

Feature Overview


  • ES2015 module syntax
  • Manage npm dependencies in IDE
  • Organize imports in IDE

Read More about Modularization with N4JS ›

Nominal And Structural Typing

  • Nominal typing (by default)
  • Structural typing
  • Combining both

Nominal And Structural Typing in N4JS ›


  • Generic classes & interfaces
  • Generic functions & methods
  • Wildcards
  • Familiar from Java

Read More about Generics in N4JS ›


  • Async functions & methods
  • Await on functions/methods returning a Promise
  • @Promisifiable and @Promisify

Read More about Async/Await with N4JS ›

Dependency Injection

  • Configure bindings with @Bind
  • Nesting injectors @WithParentInjector
  • DI support in N4JS test framework

Read More about Dependency Injection with N4JS ›


  • Built-in test support
  • Annotations @Test, @Ignore, etc.
  • IDE support for running & viewing results

Read More about Testing with N4JS ›

Node.js Support

  • On-Demand npm Installation
  • N4JS type definitions
  • npm package export feature

Read More about Node.js Support in N4JS ›

The N4JS Project

N4JS Project Status

The Eclipse N4JS project is in the Incubation Phase and there is no official Eclipse release available yet (for all releases see the download page). This doesn't mean that N4JS is unstable; we have an extensive test suite (>90.000 tests) to ensure a stable nightly build and N4JS has been in use in several large non-public projects for years. There still may be bugs (there are always bugs) and features which are under development. We encourage feedback from all users! You can ask questions about getting started with using the N4JS Language and IDE for developing your own projects at the forum or you can create bug reports and feature requests using GitHub issues at the official Eclipse repository for N4JS. Note that it's also possible to write and submit bug reports from within the N4JS IDE itself.