JSAPI

Overview

JSAPI is a Go (golang) package for embedding the spidermonkey javascript interpreter into Go projects.

Quick Tour

Exposing a Go function to javascript

Exposing a simple Go function to javascript, calling the function and printing the resulting value out.

cx := jsapi.NewContext()

cx.DefineFunction("add", func(a, b int) int {
	return a + b
})

var result int
cx.Eval(`add(1,2)`, &result) // call the go func from js

fmt.Println("result is", result)

Mapping a Go struct to a javascript Object

It is often useful to have simple struct properties visible from both Go-land and JS-land, by passing a struct to DefineObject the values will be proxied back and forth:

type Person struct {
    Name string
}
p := &Person{"jeff"}

cx := jsapi.NewContext()

cx.DefineObject("person", p) // p's public fields exposed

var name string
cx.Eval(`person.name`, &name) // Read the name from js

cx.Exec(`person.name = 'bob'`) // Set the name from js

Use a Pool of worker contexts

Avoid bottlenecks in certain loads with Pools:

// create pool of 8 worker Contexts
pool := jsapi.NewPool(8) 

// Add a sleep function to all the contexts
pool.DefineFunction("sleep", func(ms int){
	time.Sleep(time.Duration(ms) * time.Millisecond)	
})

// Spawn 100 goroutines to use the pool
wg := new(sync.WaitGroup)
for i := 0; i < 100; i++ {
	wg.Add(1)
	go func() {
		pool.Exec(`sleep(10)`)
		wg.Done()
	}()
}
wg.Wait()

Documentation

See godoc for API documentation.

Installation

Since this package relies on a C/C++ library that steps outside the realm of the go tool's capabilities you will have to perform some extra steps to get it to build.

First ensure that you have your GOPATH configured to something suitable. Then fetch and build jsapi manually using the following steps:

mkdir -p $GOPATH/src/github.com/chrisfarms/jsapi
cd $GOPATH/src/github.com/chrisfarms/jsapi
git clone --recursive https://github.com/chrisfarms/jsapi.git "."
./make.sh
go install

If all went well you should see the PASS output from the test run and the package can now be used as per usual via go install and:

import "github.com/chrisfarms/jsapi"