Go实战--golang中的JQUERY(PuerkitoBio/goquery、从html中获取链

生命不止，继续 go go go !!!
jQuery应该说是家喻户晓。

jQuery is a fast,small,and feature-rich JavaScript library. It makes things like HTML document traversal and manipulation,event handling,animation,and Ajax much simpler with an easy-to-use API that works across a multitude of browsers. With a combination of versatility and extensibility,jQuery has changed the way that millions of people write JavaScript.

jQuery 是一个 JavaScript 函数库。
jQuery 库包含以下特性：
HTML 元素选取
HTML 元素操作
CSS 操作
HTML 事件函数
JavaScript 特效和动画
HTML DOM 遍历和修改
AJAX
Utilities

在golang的世界中，
github.com/PuerkitoBio/goquery 这个库就实现了类似 jQuery 的功能，让我们能方便的使用 Go 语言操作 HTML 文档。

记住，如果使用golang做爬虫方面的事儿，你可能会用到goquery啊！

参考：
http://blog.studygolang.com/2015/04/go-jquery-goquery/

PuerkitoBio/goquery

github地址：
https://github.com/PuerkitoBio/goquery

Star: 4833

描述：
A little like that j-thing,only in Go.

获取：
go get github.com/PuerkitoBio/goquery

创建 Document 对象
goquery 暴露了两个结构体：Document 和 Selection.
Document 表示一个 HTML 文档，Selection 用于像 jQuery 一样操作，支持链式调用。goquery 需要指定一个 HTML 文档才能继续后续的操作。

查找到指定节点
Selection 有一系列类似 jQuery 的方法，Document 结构体内嵌了 *Selection，因此也能直接调用这些方法。主要的方法是 Selection.Find(selector string)，传入一个选择器，返回一个新的，匹配到的 *Selection，所以能够链式调用。

属性操作
经常需要获取一个标签的内容和某些属性值，使用 goquery 可以很容易做到

官方例子

package main

import (
  "fmt"
  "log"

  "github.com/PuerkitoBio/goquery"
)

func ExampleScrape() {
  doc,err := goquery.NewDocument("http://metalsucks.net")
  if err != nil {
    log.Fatal(err)
  }

  // Find the review items
  doc.Find(".sidebar-reviews article .content-block").Each(func(i int,s *goquery.Selection) {
    // For each item found,get the band and title
    band := s.Find("a").Text()
    title := s.Find("i").Text()
    fmt.Printf("Review %d: %s - %sn",i,band,title)
  })
}

func main() {
  ExampleScrape()
}

输出：

Review 0: Cavalera Conspiracy - Psychosis
Review 1: Cannibal Corpse - Red Before Black
Review 2: All Pigs Must Die - Hostage Animal
Review 3: Electric Wizard - Wizard Bloody Wizard
Review 4: Trivium - The Sin and the Sentence

获取所有links

import (
    "fmt"
    "log"

    "github.com/PuerkitoBio/goquery"
)

func linkScrape() {
    doc,err := goquery.NewDocument("http://jonathanmh.com")
    if err != nil {
        log.Fatal(err)
    }

    doc.Find("body a").Each(func(index int,item *goquery.Selection) {
        linkTag := item
        link,_ := linkTag.Attr("href")
        linkText := linkTag.Text()
        fmt.Printf("Link #%d: '%s' - '%s'n",index,linkText,link)
    })
}

func main() {
    linkScrape()
}

输出：

Link #0: 'Skip to content' - '#content'
Link #1: 'JonathanMH' - 'https://jonathanmh.com/'
Link #2: 'Blog' - 'https://jonathanmh.com/category/blog/'
Link #3: 'Hire Me' - 'https://jonathanmh.com/hire-me/'
Link #4: 'About' - 'https://jonathanmh.com/about/'
Link #5: 'twitter' - 'https://twitter.com/JonathanMH_com'
Link #6: 'rss feed' - 'http://jonathanmh.com/feed/'
Link #7: 'github' - 'https://github.com/JonathanMH'
Link #8: 'stackoverflow' - 'http://stackoverflow.com/users/896285/jonathan-m-hethey'
Link #9: 'instagram' - 'http://instagram.com/jonathanmh'
Link #10: 'facebook' - 'https://www.facebook.com/pages/JonathanMH/159526834122370'
Link #11: 'linkedin' - 'http://www.linkedin.com/in/jonathanmh'
Link #12: 'hire me' - '/hire-me'
Link #13: '' - 'https://twitter.com/JonathanMH_com'
Link #14: '' - 'https://www.facebook.com/JonathanMH-159526834122370/'
Link #15: '' - 'https://www.instagram.com/jonathanmh/'
Link #16: '' - 'https://github.com/jonathanmh/'
Link #17: 'Work every day like you just got fired' - 'https://jonathanmh.com/work-every-day-like-just-got-fired/'
Link #18: 'Vue.js API Client / Single Page App (SPA) Tutorial' - 'https://jonathanmh.com/vue-js-api-client-single-page-app-spa-tutorial/'
Link #19: 'Building a Simple Searchable API with Express (Backend)' - 'https://jonathanmh.com/building-a-simple-searchable-api-with-express-backend/'
Link #20: 'Music Monday: Doom Soundtrack' - 'https://jonathanmh.com/music-monday-doom-soundtrack/'
Link #21: 'Brick by Brick' - 'https://jonathanmh.com/brick-by-brick/'
Link #22: 'Taking Screenshots with Headless,The Chrome Debuggping Protocol (CDP) and Golang' - 'https://jonathanmh.com/taking-screenshots-headless-chrome-debuggping-protocol-cdp-golang/'
Link #23: 'Firefox has re-joined the Browser Wars' - 'https://jonathanmh.com/firefox-re-joined-browser-wars/'
Link #24: 'A Mastodon Review,is it the next Twitter / Facebook by the People?' - 'https://jonathanmh.com/mastodon-review-next-twitter-facebook-people/'
Link #25: 'Testing Coin Hive Crowd Source Monero Mining' - 'https://jonathanmh.com/testing-coin-hive-crowd-source-monero-mining/'
Link #26: 'Glass Half' - 'https://jonathanmh.com/glass-half/'
Link #27: 'read older posts' - '/blog/page/2/'
Link #28: 'twitter' - 'https://twitter.com/JonathanMH_com'
Link #29: 'rss feed' - 'http://jonathanmh.com/feed/'
Link #30: 'github' - 'https://github.com/JonathanMH'
Link #31: 'stackoverflow' - 'http://stackoverflow.com/users/896285/jonathan-m-hethey'
Link #32: 'instagram' - 'http://instagram.com/jonathanmh'
Link #33: 'facebook' - 'https://www.facebook.com/pages/JonathanMH/159526834122370'
Link #34: 'linkedin' - 'http://www.linkedin.com/in/jonathanmh'
Link #35: '.htaccess' - 'https://jonathanmh.com/tag/htaccess/'
Link #36: 'Adobe' - 'https://jonathanmh.com/tag/adobe/'
Link #37: 'Android' - 'https://jonathanmh.com/tag/android/'
Link #38: 'Arch Linux' - 'https://jonathanmh.com/tag/arch-linux/'
Link #39: 'atom' - 'https://jonathanmh.com/tag/atom/'
Link #40: 'bash' - 'https://jonathanmh.com/tag/bash/'
Link #41: 'blogging' - 'https://jonathanmh.com/tag/blogging/'
Link #42: 'Brackets' - 'https://jonathanmh.com/tag/brackets/'
Link #43: 'cigtrack' - 'https://jonathanmh.com/tag/cigtrack/'
Link #44: 'CodeIgniter' - 'https://jonathanmh.com/tag/codeigniter/'
Link #45: 'CSS' - 'https://jonathanmh.com/tag/css/'
Link #46: 'Digital Ocean' - 'https://jonathanmh.com/tag/digital-ocean/'
Link #47: 'express.js' - 'https://jonathanmh.com/tag/express-js/'
Link #48: 'facebook' - 'https://jonathanmh.com/tag/facebook/'
Link #49: 'ghost' - 'https://jonathanmh.com/tag/ghost/'
Link #50: 'git' - 'https://jonathanmh.com/tag/git/'
Link #51: 'github' - 'https://jonathanmh.com/tag/github/'
Link #52: 'gitlab' - 'https://jonathanmh.com/tag/gitlab/'
Link #53: 'go' - 'https://jonathanmh.com/tag/go/'
Link #54: 'golang' - 'https://jonathanmh.com/tag/golang/'
Link #55: 'Google' - 'https://jonathanmh.com/tag/google/'
Link #56: 'Gulp' - 'https://jonathanmh.com/tag/gulp/'
Link #57: 'gvim' - 'https://jonathanmh.com/tag/gvim/'
Link #58: 'JavaScript' - 'https://jonathanmh.com/tag/javascript/'
Link #59: 'kickstarter' - 'https://jonathanmh.com/tag/kickstarter/'
Link #60: 'Linux' - 'https://jonathanmh.com/tag/linux/'
Link #61: 'markdown' - 'https://jonathanmh.com/tag/markdown/'
Link #62: 'mindset' - 'https://jonathanmh.com/tag/mindset/'
Link #63: 'MVC' - 'https://jonathanmh.com/tag/mvc/'
Link #64: 'Nginx' - 'https://jonathanmh.com/tag/nginx/'
Link #65: 'node.js' - 'https://jonathanmh.com/tag/node-js/'
Link #66: 'npm' - 'https://jonathanmh.com/tag/npm/'
Link #67: 'PHP' - 'https://jonathanmh.com/tag/php/'
Link #68: 'plugin' - 'https://jonathanmh.com/tag/plugin/'
Link #69: 'Raspberry PI' - 'https://jonathanmh.com/tag/raspberry-pi/'
Link #70: 'SCSS' - 'https://jonathanmh.com/tag/scss/'
Link #71: 'social media' - 'https://jonathanmh.com/tag/social-media/'
Link #72: 'ssh' - 'https://jonathanmh.com/tag/ssh/'
Link #73: 'Terminal' - 'https://jonathanmh.com/tag/terminal/'
Link #74: 'toolbox' - 'https://jonathanmh.com/tag/toolbox/'
Link #75: 'UberWriter' - 'https://jonathanmh.com/tag/uberwriter/'
Link #76: 'Ubuntu' - 'https://jonathanmh.com/tag/ubuntu/'
Link #77: 'vim' - 'https://jonathanmh.com/tag/vim/'
Link #78: 'web crawling' - 'https://jonathanmh.com/tag/web-crawling/'
Link #79: 'WordPress' - 'https://jonathanmh.com/tag/wordpress/'
Link #80: 'Blog' - 'https://jonathanmh.com/category/blog/'
Link #81: 'Hire Me' - 'https://jonathanmh.com/hire-me/'
Link #82: 'About' - 'https://jonathanmh.com/about/'
Link #83: 'twitter' - 'https://twitter.com/JonathanMH_com'
Link #84: 'rss feed' - 'http://jonathanmh.com/feed/'
Link #85: 'github' - 'https://github.com/JonathanMH'
Link #86: 'stackoverflow' - 'http://stackoverflow.com/users/896285/jonathan-m-hethey'
Link #87: 'instagram' - 'http://instagram.com/jonathanmh'
Link #88: 'facebook' - 'https://www.facebook.com/pages/JonathanMH/159526834122370'
Link #89: 'linkedin' - 'http://www.linkedin.com/in/jonathanmh'
Link #90: 'JonathanMH' - 'https://jonathanmh.com/'
Link #91: 'Proudly powered by WordPress' - 'https://wordpress.org/'

Convert All HTML Links to reStructuredText via goquery

package main

import (
    "os"
    "strings"
    "text/template"

    "github.com/PuerkitoBio/goquery"
)

const rstLink = "`{{.Text}} <{{.Href}}>`_n"

type htmlLink struct {
    Text string
    Href string
}

func main() {
    url := "https://www.baidu.com"

    doc,err := goquery.NewDocument(url)
    if err != nil {
        panic(err)
    }

    tmpl := template.Must(template.New("test").Parse(rstLink))
    doc.Find("a").Each(func(_ int,link *goquery.Selection) {
        text := strings.TrimSpace(link.Text())
        href,ok := link.Attr("href")
        if ok {
            tmpl.Execute(os.Stdout,&htmlLink{text,href})
        }
    })
}

输出：

` </>`_
`手写 <javascript:;>`_
`拼音 <javascript:;>`_
`关闭 <javascript:;>`_
`百度首页 </>`_
`设置 <javascript:;>`_
`登录 <https://passport.baidu.com/v2/?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F>`_
`新闻 <http://news.baidu.com>`_
`hao123 <http://www.hao123.com>`_
`地图 <http://map.baidu.com>`_
`视频 <http://v.baidu.com>`_
`贴吧 <http://tieba.baidu.com>`_
`学术 <http://xueshu.baidu.com>`_
`登录 <https://passport.baidu.com/v2/?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F>`_
`设置 <http://www.baidu.com/gaoji/preferences.html>`_
`更多产品 <http://www.baidu.com/more/>`_
`新闻 <http://news.baidu.com/ns?cl=2&rn=20&tn=news&word=>`_
`贴吧 <http://tieba.baidu.com/f?kw=&fr=wwwt>`_
`知道 <http://zhidao.baidu.com/q?ct=17&pn=0&tn=ikaslist&rn=10&word=&fr=wwwt>`_
`音乐 <http://music.baidu.com/search?fr=ps&ie=utf-8&key=>`_
`图片 <http://image.baidu.com/search/index?tn=baiduimage&ps=1&ct=201326592&lm=-1&cl=2&nc=1&ie=utf-8&word=>`_
`视频 <http://v.baidu.com/v?ct=301989888&rn=20&pn=0&db=0&s=25&ie=utf-8&word=>`_
`地图 <http://map.baidu.com/m?word=&fr=ps01000>`_
`文库 <http://wenku.baidu.com/search?word=&lm=0&od=0&ie=utf-8>`_
`更多? <//www.baidu.com/more/>`_
`把百度设为主页 <//www.baidu.com/cache/sethelp/help.html>`_
`关于百度 <http://home.baidu.com>`_
`About  Baidu <http://ir.baidu.com>`_
`百度推广 <http://e.baidu.com/?refer=888>`_
`使用百度前必读 <http://www.baidu.com/duty/>`_
`意见反馈 <http://jianyi.baidu.com/>`_
`京公网安备11000002000001号 <http://www.beian.gov.cn/portal/registerSystemInfo?recordcode=11000002000001>`_