Go每日一库之136：gopherjs（将Go代码编译成JS）-526互联

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：
每日一库之136：gopherjs（将Go代码编译成JS）-0