CandyJS is an intent of create a fully transparent bridge between Go and the JavaScript engine duktape. Basicly is a syntax-sugar library built it on top of go-duktape using reflection techniques.

This is a fork of https://github.com/mcuadros/go-candyjs.

It encodes UTF-8 strings passed to duktape into CESU-8.

It decodes strings returned by duktape from CESU-8 into UTF-8.

It uses https://github.com/crazytyper/go-cesu8 to encode/decode CESU-8.

ok but what for ...

build extensible applications that allow to the user execute arbitrary code (let's say plugins) without the requirement of compile it.

Demo

Features

Embeddable Ecmascript E5/E5.1 compliant engine (duktape).

ctx := candyjs.NewContext()
ctx.EvalString(`
  function factorial(n) {
    if (n === 0) return 1;
    return n * factorial(n - 1);
  }

  print(factorial(10));
`)  //3628800

Call Go functions from JavaScript and vice versa.

ctx := candyjs.NewContext()
ctx.PushGlobalGoFunction("golangMultiply", func(a, b int) int {
    return a * b
})

ctx.EvalString(`print(golangMultiply(5, 10));`) //50

Transparent interface between Go structs and JavaScript.

type MyStruct struct {
    Number int
}

func (m *MyStruct) Multiply(x int) int {
    return m.Number * x
}
...
ctx := candyjs.NewContext()
ctx.PushGlobalStruct("golangStruct", &MyStruct{10})

ctx.EvalString(`print(golangStruct.number);`) //10
ctx.EvalString(`print(golangStruct.multiply(5));`) //50

Import of Go packages into the JavaScript context.

//go:generate candyjs import fmt
...
ctx := candyjs.NewContext()
ctx.EvalString(`
    var fmt = CandyJS.require('fmt');
    fmt.printf('candyjs is %s', 'awesome')
`) // 'candyjs is awesome'

Installation

The recommended way to install go-candyjs is:

go get -u github.com/crazytyper/go-candyjs/...

CandyJS includes a binary tool used by go generate, please be sure that $GOPATH/bin is on your $PATH

Examples

JavaScript running a HTTP server

In this example a gin server is executed and a small JSON is server. In CandyJS you can import Go packages directly if they are defined previously on the Go code.

Interpreter code (main.go)

...
//go:generate candyjs import time
//go:generate candyjs import github.com/gin-gonic/gin
func main() {
    ctx := candyjs.NewContext()
    ctx.PevalFile("example.js")
}

Program code (example.js)

var time = CandyJS.require('time');
var gin = CandyJS.require('github.com/gin-gonic/gin');

var engine = gin.default();
engine.get("/back", CandyJS.proxy(function(ctx) {
  var future = time.date(2015, 10, 21, 4, 29 ,0, 0, time.UTC);
  var now = time.now();

  ctx.json(200, {
    future: future.string(),
    now: now.string(),
    nsecs: future.sub(now)
  });
}));

engine.run(':8080');

Caveats

Due to an incompatibility with Duktape's error handling system and Go, you can't throw errors from Go. All errors generated from Go functions are generic ones error error (rc -100)

License

MIT, see LICENSE