README

nodejs-golang

Module for running Golang scripts using wasm in Node.js child processes

During module installation npm i nodejs-golang Go programming language will be downloaded and installed
In the root of the projects will be created default go_modules directory

In go_modules directory will be created main.go file. Example:

package main

import (
    "fmt"
)

func main() {
    fmt.Print("Hello, go 1.16.2")
}

Default main.wasm file will be compiled (also can be found in go_modules directory)
You need to put you code into main.go file
To rewrite main.wasm with actual info run:
```
node ./node_modules/nodejs-golang/build.js
```
Recommendation: add watcher on main.go file to rewrite main.wasm on every "save" event

Also you can run build command in code:
```
const { build } = require('nodejs-golang');
...
await build();
```
To make result of main.go execution available for Node.js - finish you code with fmt.Print(MY_RESULT) to write it to stdout

To get result of main.wasm execution - use run function

const { run } = require('nodejs-golang');
...
const MY_RESULT = await run();

Since nodejs-golang version 0.0.4 there is possibility to create, build and run multiple golang scripts in one project

GO_MODULE_NAME is the Node.js environment variable for initialization and building needed script in go_modules directory

Module initialization:

GO_MODULE_NAME=my_go_module node ./node_modules/nodejs-golang/init.js

Also you can run init command in code:

const { init } = require('nodejs-golang');
...
await init('my_go_module');

In go_modules/my_go_module directory will be created main.go file. Example:

package main

import (
    "fmt"
)

func main() {
    fmt.Print("Hello, go 1.16.2")
}

Default main.wasm file will be compiled (also can be found in go_modules/my_go_module directory)
You need to put you code into main.go file
To rewrite main.wasm with actual info run:
```
GO_MODULE_NAME=my_go_module node ./node_modules/nodejs-golang/build.js
```
Recommendation: add watcher on main.go files to rewrite main.wasm on every "save" event

Also you can run build command in code:
```
const { build } = require('nodejs-golang');
...
await build('my_go_module');
```
To make result of main.go execution available for Node.js - finish you code with fmt.Print(MY_RESULT) to write it to stdout

To get result of main.wasm execution - use run function

const { run } = require('nodejs-golang');
...
const MY_RESULT = await run('my_go_module');

Since nodejs-golang version 0.0.5 there is possibility to use Golang functions in Node.js

Recommendation: because go functions will be set as global better to use specific naming. Example: go_MY_FUNCTION_NAME

In main.go file create a function like this (there are some requirements):
```
package main

import (
    "syscall/js"
)

func myFunction(...) interface{} {
    ...
    return js.ValueOf(MY_VALUE)
}

func main() {
    c := make(chan struct{}, 0)
    js.Global().Set("go_MY_FUNCTION_NAME", js.FuncOf(myFunction))
    <-c
}
```
Requirements:

a) there must be an import of "syscall/js"

b) "myFunction" must be set to "global" js object with some name (better to keep some naming convention). For example: go_MY_FUNCTION_NAME

c) use make function to initialize channel
"instantiate" method should be run with the name of your module as a parameter while application start (or just before you need to use Golang function)
```
const { instantiate } = require('nodejs-golang');
...
await instantiate('my_go_module');
```
You can use methods from Golang anywhere in your application
```
const MY_VALUE = go_MY_FUNCTION_NAME();
```

Linux only, Node.js 14+, Go 1.16.2