Engine

A javascript Engine base on Goja inspired by k6

Limitations and modifications

• Top level async/await not supported by Goja
• ES6+ partially implemented by Goja
• Async operations should wait for ends with engine.StopEventLoopXXX
• Module includes remote/local/GoModule support by translate to CommonJs (EsBuild)

Sample

no time limit

package main

import (
   "github.com/ZenLiuCN/engine"
)
func main() {
   vm := engine.Get()
   defer vm.Free()
   v, err := vm.RunJs(
      `
console.log("Begin "+"For timeout")
new Promise((r, j) => {
    console.log("job 0")
    setTimeout(()=>r(1),1000)
}).then(v => {
    console.log("job",v)
    return new Promise((r, j) => {
        setTimeout(()=>r(v+1),1000)
    })}).then(v => {
    console.log("job",v)
    return new Promise((r, j) => {
        setTimeout(()=>r(v+1),1000)
    })
}).then(v => {
    console.log("job",v)
    return new Promise((r, j) => {
       setTimeout(()=>r(v+1),2000)
    })
}).then(v => {
    console.log("job",v)
    return new Promise((r, j) => {
       setTimeout(()=>r(v+1),2000)
    })
})`)
   halts := vm.Await() //manual await task done
   if !halts.IsZero(){
	   panic("task not done")
   }
   if err!=nil{
      panic(err)
   }
   println(v)
}

manual

package main

import (
   "github.com/ZenLiuCN/engine"
   "time"
)
func main() {
   vm := engine.Get()
   defer vm.Free()
   v, err := vm.RunJs(
      `
console.log("Begin "+"For timeout")
new Promise((r, j) => {
    console.log("job 0")
    setTimeout(()=>r(1),1000)
}).then(v => {
    console.log("job",v)
    return new Promise((r, j) => {
        setTimeout(()=>r(v+1),1000)
    })}).then(v => {
    console.log("job",v)
    return new Promise((r, j) => {
        setTimeout(()=>r(v+1),1000)
    })
}).then(v => {
    console.log("job",v)
    return new Promise((r, j) => {
       setTimeout(()=>r(v+1),2000)
    })
}).then(v => {
    console.log("job",v)
    return new Promise((r, j) => {
       setTimeout(()=>r(v+1),2000)
    })
})`)
   halts := vm.AwaitTimeout(time.Second * 5) //manual await task done for limited time
   if !halts.IsZero(){
	   panic("task not done within 5 seconds")
   }
   if err!=nil{
      panic(err)
   }
   println(v)
}

automatic

package main

import (
	"github.com/ZenLiuCN/engine"
	"time"
)

func main() {
	vm := engine.Get()
	defer vm.Free()
	v, err := vm.RunJsTimeout(`import {Second, sleep} from 'go/time'

new Promise((r, j) => {
    sleep(Second)
    r(1)
}).then(v => {
    console.log(v)
    return new Promise((r, j) => {
        sleep(Second)
        r(v+1)
    })
}).then(v => {
    console.log(v)
    return new Promise((r, j) => {
        sleep(Second)
        r(v+1)
    })
}).then(v => {
    console.log(v)
    return new Promise((r, j) => {
        sleep(Second*2)
        r(v+1)
    })
}).then(v => {
    console.log(v)
    return new Promise((r, j) => {
        sleep(Second*2)
        r(v+1)
    })
})
`, time.Second*8)
	if err != nil {
		panic(err) // if error is ErrTimeout, the value is HaltJobs
	}
	println(v)
}

Extensions

Engine

Simple wrapper for goja.Runtime with extended abilities.

Code

Simple wrapper for goja.Program

Naming

1. use struct tag js:"name" to mapping fields to js property
2. use struct tag js:"-" to ignore export field
3. default strategy for both functions methods and fields
   • UUUlllUll => uuUllUll
   • UlllUll => ullUll
   • XlllUll => llUll
   • XUllUll => UllUll

Resolver with require

Simple support for CommonJs, ES script and TypeScript also compiled as CJS script, inspire by k6

Module System

1. Module: a simple global instance
2. InitializeModule: a module instanced when register to an Engine
3. TopModule: a module register some top level function or objects
4. TypeDefined: a module contains d.ts data
5. GoModule: a module for expose golang into js (use by import module)

compiler module

• go/compiler built-in compiler for both typescript and javascript
• go/esbuild expose esbuild to js

components

• esbuild

engine module

• go/engine: use engine in scripts, maybe not to use too many russian dolls

console module

• global : slog console or byte buffer console

buffer module

• go/buffer: golang byte slice and bytes.Buffer

hash module

• go/hash:golang hash functions
• go/codec:golang codec functions, include base64 ...

crypto module

• go/crypto : golang crypto

os module

• go/os : golang os , not full functions

io module

• go/io : golang io module

chan module

• go/chan : golang chan type only

Modules

pluggable modules

sqlx

• go/sqlx: sqlx with pgx mysql and sqlite driver

components

• sqlx,
• sqlite
• mysql modified see source at sqlx/mysql

Excelize

• go/excel: excel reading or generate

components

• excelize

fetch

• go/fetch: base function done, improve for compact with browser fetch.

pug

• go/pug: jade(pug) compiler

components

• jade

minify

• go/minify: file minify

components

• minify

pdf

dev

jose

draft

http

draft