简介
GopherJS 可以将 Go 代码编译成纯 JavaScript 代码。其主要目的是为了让你可以使用 Go 来编写前端代码，这些代码可执行在浏览器上运行。你可以通过这里尝试下 GopherJS： GopherJS Playground.
例如 JavaScript 代码：
document.write("Hello world!");
用 GopherJS 来写就变成这样：
js.Global.Get("document").Call("write", "Hello world!")
好像复杂了不少，函数调用这样：
package main
import "github.com/gopherjs/gopherjs/js"
func main() {
js.Global.Set("myLibrary", map[string]interface{}{
"someFunction": someFunction,
})
}
func someFunction() {
//...
}
安装
go get -u github.com/gopherjs/gopherjs
// or
go install github.com/gopherjs/gopherjs@latest
简单Demo
进行pi 运算，结果还真是快
package main
import (
"fmt"
"math"
"time"
)
func term(k float64) float64 {
return 4 * math.Pow(-1, k) / (2*k + 1)
}
// pi performs n iterations to compute an approximation of pi using math.Pow.
func pi(n int32) float64 {
f := 0.0
for k := int32(0); k <= n; k++ {
f += term(float64(k))
}
return f
}
func main() {
// Start measuring time from now.
started := time.Now()
const n = 50 * 1000 * 1000
fmt.Printf("approximating pi with %v iterations.\n", n)
fmt.Println(pi(n))
fmt.Println("total time taken is:", time.Since(started))
}
一般我们使用go run 运行code；
但是使用gopherjs 我们用 gopherjs run。
运行：
$ go run main.go
approximating pi with 50000000 iterations.
3.1415926735902504
total time taken is: 5.823561654s
$ gopherjs run main.go
gopherjs: Source maps disabled. Install source-map-support module for nice stack traces. See https://github.com/gopherjs/gopherjs#gopherjs-run-gopherjs-test.
approximating pi with 50000000 iterations.
3.1415926735902504
total time taken is: 2.534s
web 场景应用（主要是一些bindings）
package main
import (
"fmt"
"github.com/gopherjs/gopherjs/js"
)
func main() {
fmt.Println("Hello, playground")
js.Global.Call("alert", "Hello, JavaScript")
println("Hello, JS console")
}
编译为JS代码：
gopherjs build app.go
html 页面引用:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script type="text/javascript" src="./app.js"></script>
</body>
</html>
打开html：
适用场景
后端golang 编写一次，多次使用，同时性能还不错，目前官方提供了好多方便的binding。
比如基于electron 开发的应用使用 gopherjs-electron会有比较大的性能提升，很不错的项目。
References
https://github.com/oskca/gopherjs-electron
https://github.com/gopherjs/gopherjs
https://github.com/rongfengliang/gopherjs-demo