Goja Tools

Export go package to goja

Goja is an excellent script engine for Go. It can export a Go value to JS engine easily, but you may feel troublesome when deal with a package.

So, I wrote the Goja Tools.

It anaylizes the input go code, then generates a go map, that contains all funcs and values of the src code.

Also, it generates a .ts file for code hints.

Usage

Install

go install -v github.com/garfeng/gojatools/cmd/goja_imports@latest

Command

goja_imports -p <dst pkg name> -i <src pkg path> -go <dst go code path> -ja <dst js code path>

# For example:

goja_imports -p js -i compress/gzip -go js/compress.gzip.go -ja js/compress.gzip.ts
goja_imports -p js -i image -go js/image.go -ja js/image.ts

Help:

goja_imports --help
  -go string
        dst go file (default "js/js.go")
  -i string
        input package path
  -ja string
        dst typescript file (default "js/js.ts")
  -p string
        dst package name

Example

More examples

Go:

// Code generated by "goja_imports -p js -i io/ioutil -go io.ioutil.go -ja io.ioutil.ts"; DO NOT EDIT.
// Install by "go get -u -v github.com/garfeng/gojatools/cmd/goja_imports";
//go:generate goja_imports -p js -i io/ioutil -go io.ioutil.go -ja io.ioutil.ts

package js

import (
	"github.com/garfeng/gojatools/importgo"
	origin "io/ioutil"
)

var ExportJS_IO_IOUTIL = map[string]interface{}{

	// Value

	"Discard": origin.Discard, // io.Writer |

	// Function

	// WriteFile writes data to a file named by filename.
	// If the file does not exist, WriteFile creates it with permissions perm
	// (before umask); otherwise WriteFile truncates it before writing, without changing permissions.
	//
	// As of Go 1.16, this function simply calls os.WriteFile.
	//func WriteFile( filename string, data []byte, perm fs.FileMode,)  (	_ error, )
	"WriteFile": origin.WriteFile,

    // ... other codes

	// ReadAll reads from r until an error or EOF and returns the data it read.
	// A successful call returns err == nil, not err == EOF. Because ReadAll is
	// defined to read from src until EOF, it does not treat an EOF from Read
	// as an error to be reported.
	//
	// As of Go 1.16, this function simply calls io.ReadAll.
	//func ReadAll( r io.Reader,)  (	_ []byte, 	_ error, )
	"ReadAll": origin.ReadAll,

	// NopCloser returns a ReadCloser with a no-op Close method wrapping
	// the provided Reader r.
	//
	// As of Go 1.16, this function simply calls io.NopCloser.
	//func NopCloser( r io.Reader,)  (	_ io.ReadCloser, )
	"NopCloser": origin.NopCloser,
}

func init() {
	importgo.Add("io.ioutil", "ioutil", ExportJS_IO_IOUTIL)
}

Typescript:

import io from "./io"

namespace ioutil {

export const Discard: io.Writer = origin.Discard; 

// WriteFile writes data to a file named by filename.
// If the file does not exist, WriteFile creates it with permissions perm
// (before umask); otherwise WriteFile truncates it before writing, without changing permissions.
// 
// As of Go 1.16, this function simply calls os.WriteFile.
export function WriteFile(filename: string, data: byte[], perm: fs.FileMode) : error {
    
    return origin.WriteFile()
}

// ... other codes

// ReadAll reads from r until an error or EOF and returns the data it read.
// A successful call returns err == nil, not err == EOF. Because ReadAll is
// defined to read from src until EOF, it does not treat an EOF from Read
// as an error to be reported.
// 
// As of Go 1.16, this function simply calls io.ReadAll.
export function ReadAll(r: io.Reader) : byte[] {
    
    return origin.ReadAll()
}

// NopCloser returns a ReadCloser with a no-op Close method wrapping
// the provided Reader r.
// 
// As of Go 1.16, this function simply calls io.NopCloser.
export function NopCloser(r: io.Reader) : io.ReadCloser {
    
    return origin.NopCloser()
}

}

export default ioutil;

If the method has multiple outputs, the ts code will be:

export class RuneScanner { 
    UnreadRune() : error {
        
        return origin.UnreadRune();
    }

    // multiple returns
    ReadRune() : [rune, int] {
        return origin.ReadRune();
    }
    
}

The generated file tree

$ tree js/
js
├── bytes.go
├── bytes.ts
├── image.color.go
├── image.color.ts
├── image.go
├── image.png.go
├── image.png.ts
├── image.ts
├── io.ioutil.go
├── io.ioutil.ts
├── os.go
└── os.ts

0 directories, 12 files

OS support

• Windows (Windows 11 x64)
• Linux (Kubuntu 22.04 LTS x64)
• Darwin (no machine to test)

Thanks

• Goja
• Gotype

This tool would not exist without them.