# 如何使用 Golang + selenium 操作瀏覽器

## 環境建立
1. 取得selenium package
https://github.com/tebeka/selenium

執行文件裡Installing指令即可

go get -t -d github.com/tebeka/selenium

因為我的OS是Windows，沒辦法用文件裡Downloading Dependencies的例子(那是linux)，所以要自己找到瀏覽器的Binary檔

2. 下載ChromeDriver Binary
[官網下載](https://sites.google.com/chromium.org/driver/)，記得要配合自己的Chrome版本下載
3. 建議把下載的ChromeDriver Binary放在main package的資料夾內
## Hello World
使用[如何使用 Golang 操作瀏覽器](https://opensourcedoc.com/selenium/manipulate-selenium-with-golang/)的例子，但<font color=red>要設定ChromeDriver Binary檔的路徑(第20行)</font>

import (
	"fmt"
	"os"
	"time"

	"github.com/tebeka/selenium"
)

const (
	port = 8080
)

func main() {
	opts := []selenium.ServiceOption{
		// Enable fake XWindow session.
		// selenium.StartFrameBuffer(),
		selenium.Output(os.Stderr), // Output debug information to STDERR
		//設定ChromeDriver Binary檔的路徑
		//因為我把下載的ChromeDriver Binary放在main資料夾內，所以用相對路徑設定就好
        //這個設定在20221005被發現沒有作用，可能是我誤解了他的用法，也可能是go升版1.19後的關係，總之先註解
		//selenium.ChromeDriver("main"),
	}

	// Enable debug info.
	// selenium.SetDebug(true)
	//這裡用相對路徑的方式去寫chromedriver的位置
	service, err := selenium.NewChromeDriverService("./chromedriver", port, opts...)
	if err != nil {
		panic(err)
	}
	defer service.Stop()

	caps := selenium.Capabilities{"browserName": "chrome"}
	wd, err := selenium.NewRemote(caps, fmt.Sprintf("http://127.0.0.1:%d/wd/hub", port))
	if err != nil {
		panic(err)
	}
	defer wd.Quit()

	wd.Get("https://tw.yahoo.com")

	time.Sleep(5 * time.Second)
}

## 用selenium操作網頁
[參考官網](https://github.com/tebeka/selenium/blob/master/example_test.go)去改

package main

import (
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/tebeka/selenium"
)

const (
	port = 8080
)

func main() {
	opts := []selenium.ServiceOption{
		// Enable fake XWindow session.
		// selenium.StartFrameBuffer(),
		selenium.Output(os.Stderr), // Output debug information to STDERR
		//設定ChromeDriver Binary檔的路徑
        //因為我把下載的ChromeDriver Binary放在main資料夾內，所以用相對路徑設定就好
		selenium.ChromeDriver("main"),
	}

	// Enable debug info.
	// selenium.SetDebug(true)
	service, err := selenium.NewChromeDriverService("chromedriver", port, opts...)
	if err != nil {
		panic(err)
	}
	defer service.Stop()

	caps := selenium.Capabilities{"browserName": "chrome"}
	wd, err := selenium.NewRemote(caps, fmt.Sprintf("http://127.0.0.1:%d/wd/hub", port))
	if err != nil {
		panic(err)
	}
	defer wd.Quit()

	// Navigate to the simple playground interface.
	url := "https://go.dev/play/"

	if err := wd.Get(url); err != nil {
		panic(err)
	}

	// Get a reference to the text box containing code.
	elem, err := wd.FindElement(selenium.ByCSSSelector, "#code")
	if err != nil {
		panic(err)
	}
	// Remove the boilerplate code already in the text box.
	if err := elem.Clear(); err != nil {
		panic(err)
	}

	// Enter some new code in text box.
	keys := `package main
	import "fmt"
	func main() {
	fmt.Println("Hello WebDriver!")
	}`

	err = elem.SendKeys(keys)
	if err != nil {
		panic(err)
	}

	// Click the run button.
	btn, err := wd.FindElement(selenium.ByCSSSelector, "#run")
	if err != nil {
		panic(err)
	}
	if err := btn.Click(); err != nil {
		panic(err)
	}

	// Wait for the program to finish running and get the output.
	outputDiv, err := wd.FindElement(selenium.ByTagName, "pre")
	if err != nil {
		panic(err)
	}

	var output string
	for {
		output, err = outputDiv.Text()
		if err != nil {
			panic(err)
		}
		if output != "Waiting for remote server..." {
			break
		}
		time.Sleep(time.Millisecond * 100)
	}

	fmt.Printf("%s", strings.Replace(output, "\n\n", "\n", -1))

	time.Sleep(10 * time.Second)
}

印出

Hello WebDriver!
Program exited.

## 參考資料
* 如何使用 Golang 操作瀏覽器
>https://opensourcedoc.com/selenium/manipulate-selenium-with-golang/
* The most complete, best-tested WebDriver client for Go
>https://github.com/tebeka/selenium
>https://github.com/tebeka/selenium/blob/master/example_test.go
* ChromeDriver官網
>https://sites.google.com/chromium.org/driver/