djs

dukgo, makes duktape be embedded easily

Duktape is a thin, embeddable javascript engine. Its api is very well documented. For most of developers who are not familiar with C language, it is very tedious to call duk_push_xxx() and duk_pop() to make use of the power of Duktape. Though there are some binding implementations of Duktape for languages other than C, most of them inherit the methods of using API of Duktape.

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

Install

The package is fully go-getable, So, just type

go get github.com/rosbit/dukgo

to install.

Usage

1. Evaluates expressions

package main

import (
  djs "github.com/rosbit/dukgo"
  "fmt"
)

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

  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 (
  djs "github.com/rosbit/dukgo"
  "fmt"
)

var add func(int, int)int

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

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

  // method 1: bind JS function with a golang var
  if err := ctx.BindFunc("add", &add); err != nil {
     fmt.Printf("%v\n", err)
     return
  }
  res := add(1, 2)

  // method 2: call JS function using CallFunc
  res, err := ctx.CallFunc("add", 1, 2)
  if err != nil {
     fmt.Printf("%v\n", err)
     return
  }

  fmt.Println("result is:", res)
}

3. Javascript calls Go function

Javascript calling Go function is also easy. In the Go code, calling EvalFile with a map as env will make Golang functions as Javascript global functions. There's the example:

package main

import "github.com/rosbit/dukgo"

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

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

  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.