gopherjs

GopherJS - A compiler from Go to JavaScript

GopherJS compiles Go code (golang.org) to pure JavaScript code. Its main purpose is to give you the opportunity to write front-end code in Go which will still run in all browsers. Give GopherJS a try on the GopherJS Playground.

You can take advantage of Go's elegant type system and other compile-time checks that can have a huge impact on bug detection and the ability to refactor, especially for big projects. Just think of how often a JavaScript method has extra handling of some legacy parameter scheme, because you don't know exactly if some other code is still calling it in that old way or not. GopherJS will tell you and if it does not complain, you can be sure that this kind of bug is not present any more.

Design Goals

• performance of generated code (see HTML5 game engine benchmark by Joseph Hager)
• similarity between Go code and generated JavaScript code for easier debugging
• compatibility with existing libraries (see the list of bindings to JavaScript APIs and libraries)
• small size of generated code

What is supported?

In one sentence: Everything except goroutines. Yes, I know that you want goroutines and I am working heavily on them. But hey, it is still better to write Go with callbacks than JavaScript with callbacks, right? A lot of Go's packages do already work, see the compatibility table. If you want this still missing feature, please consider to support this project with a star to show your interest.

Installation and Usage

Get or update GopherJS and dependencies with:

go get -u github.com/gopherjs/gopherjs

Now you can use ./bin/gopherjs build [files] or ./bin/gopherjs install [package] which behave similar to the go tool. For main packages, these commands create a .js file and .js.map source map in the current directory or in $GOPATH/bin. The generated JavaScript file can be used as usual in a website. Use ./bin/gopherjs help [command] to get a list of possible command line flags, e.g. for minification and automatically watching for changes. If you want to run the generated code with Node.js, see this page.

Note: GopherJS will try to write compiled object files of the core packages to your $GOROOT/pkg directory. If that fails, it will fall back to $GOPATH/pkg.

Getting started

1. Interacting with the DOM

Accessing the DOM directly via the js package (see below) is possible, but using a JavaScript framework is more elegant. Take a look at the TodoMVC Example which is using the jQuery bindings or alternatively the AngularJS bindings. Additionally, there is a list of bindings to JavaScript APIs and libraries by community members.

2. Providing library functions for use in other JavaScript code

Set a global variable to a map that contains the functions:

package main

import "github.com/gopherjs/gopherjs/js"

func main() {
  js.Global.Set("myLibrary", map[string]interface{}{
    "someFunction": someFunction,
  })
}

func someFunction() {
  [...]
}

For more details see Jason Stone's blog post about GopherJS.

Interface to native JavaScript

The package github.com/gopherjs/gopherjs/js provides functions for interacting with native JavaScript APIs. Please see its documentation for further details.

Community

• Get help in the Google Group
• See the list of bindings to JavaScript APIs and libraries by community members
• Follow GopherJS on Twitter

Roadmap

These features are not implemented yet, but on the roadmap:

• goroutines, channels, select
• float32 and complex64 currently have the same precision as float64 and complex128