quickjs

go-quickjs, make quickjs be embedded easily

QuickJS is a small and embeddable Javascript engine written by Fabrice Bellard.

go-quickjs is a package wrapping quickjs and making it a pragmatic embedding language. With some helper functions provided by go-quickjs, calling Golang functions from Javascript, or calling Javascript functions from Golang are both very simple. So, with the help of go-quickjs, quickjs can be embedded in Golang application easily.

Install

To install go-quickjs, following the steps (under Linux/macos):

1. make sure gcc, make, wget are ready
2. run git clone github.com/rosbit/go-quickjs to clone the source
3. cd go-quickjs to change the directory
4. run make to build the libquickjs.a
5. optionally run go build.

Usage

1. Evaluates expressions

package main

import (
  "github.com/rosbit/go-quickjs"
  "fmt"
)

func main() {
  ctx, err := quickjs.NewContext()
  if err != nil {
    fmt.Printf("%v\n", err)
    return
  }
  defer ctx.Free()

  res, _ := ctx.Eval("a + b", map[string]interface{}{
     "a": 10,
     "b": 1,
  })
  fmt.Println("result is:", res)
}

2. Go calls Javascript function

Suppose there's a Javascript file named a.js like this:

function add(a, b) {
    return a+b
}

one can call the Javascript function add() in Go code like the following:

package main

import (
  "github.com/rosbit/go-quickjs"
  "fmt"
)

var add func(int, int)int

func main() {
  ctx, err := quickjs.NewContext()
  if err != nil {
     fmt.Printf("%v\n", err)
     return
  }
  defer ctx.Free()

  if _, err := ctx.EvalFile("a.js", nil); err != nil {
     fmt.Printf("%v\n", err)
     return
  }

  if err := ctx.BindFunc("add", &add); err != nil {
     fmt.Printf("%v\n", err)
     return
  }

  res := add(1, 2)
  fmt.Println("result is:", res)
}

3. Javascript calls Go function

Javascript calling Go function is also easy. In the Go code, make a Golang function as Javascript global function by calling EvalFile by registering. There's the example:

package main

import "github.com/rosbit/go-quickjs"

// function to be called by Javascript
func adder(a1 float64, a2 float64) float64 {
    return a1 + a2
}

func main() {
  ctx, err := quickjs.NewContext()
  if err != nil {
      fmt.Printf("%v\n", err)
      return
  }
  defer ctx.Free()

  if _, err := ctx.EvalFile("b.js", map[string]interface{}{
      "adder": adder,
  })  // b.js containing code calling "adder"
}

In Javascript code, one can call the registered function directly. There's the example b.js.

r = adder(1, 100)   // the function "adder" is implemented in Go
console.log(r)

Status

The package is not fully tested, so be careful.

Contribution

Pull requests are welcome! Also, if you want to discuss something send a pull request with proposal and changes. Convention: fork the repository and make changes on your fork in a feature branch.