在 R 中抓取 Javascript 渲染的网页引用外部 javascript 脚本

Question

我正在尝试抓取此网页：https://www.mustardbet.com/sports/events/302698

由于网页似乎是动态呈现的，所以我按照本教程进行操作： https://www.datacamp.com/community/tutorials/scraping-javascript-generated-data-with-r#gs.dZEqev8

按照教程的建议，我使用以下代码保存了一个名为 "scrape_mustard.js" 的文件：

// scrape_mustard.js

var webPage = require('webpage');
var page = webPage.create();

var fs = require('fs');
var path = 'mustard.html'

page.open('https://www.mustardbet.com/sports/events/302698', function (status) {
  var content = page.content;
  fs.write(path,content,'w')
  phantom.exit();
});

然后，我执行

system("./phantomjs scrape_mustard.js")

但我收到错误消息：

ReferenceError: Can't find variable: Set

  https://www.mustardbet.com/assets/js/index.dfd873fb.js:1
  https://www.mustardbet.com/assets/js/index.dfd873fb.js:1 in t
  https://www.mustardbet.com/assets/js/index.dfd873fb.js:1
  https://www.mustardbet.com/assets/js/index.dfd873fb.js:1 in t
  https://www.mustardbet.com/assets/js/index.dfd873fb.js:1
  https://www.mustardbet.com/assets/js/index.dfd873fb.js:1 in t
  https://www.mustardbet.com/assets/js/index.dfd873fb.js:1
  https://www.mustardbet.com/assets/js/index.dfd873fb.js:1 in t
  https://www.mustardbet.com/assets/js/index.dfd873fb.js:1

现在，当我将“https://www.mustardbet.com/assets/js/index.dfd873fb.js”粘贴到我的浏览器时，我可以看到它是 javascript，我可能需要 (1) 将其另存为文件，或 (2) 将其包含在 scrape_mustard.js 中。

但是如果 (1)，我不知道如何引用那个新文件，如果 (2)，我不知道如何正确定义所有 javascript 以便它可以被使用。

我是javascript的新手，但也许这道题并不太难？

感谢您的帮助！

Answer 1

我能够使用 js 模块进行抓取 puppeteer.js。

下载node.jshere。 node.js 附带 npm，这让您在安装模块时更轻松。您需要使用 npm 安装 puppeteer。

在 RStudio 中，确保在安装 puppeteer.js 时位于工作目录中。安装 node.js 后，执行 (source):

system("npm i puppeteer")

scrape_mustard.js:

// load modules
const fs = require("fs");
const puppeteer = require("puppeteer");

// page url
url = "https://www.mustardbet.com/sports/events/302698";

scrape = async() => {
    const browser = await puppeteer.launch({headless: false}); // open browser
    const page = await browser.newPage(); // open new page
    await page.goto(url, {waitUntil: "networkidle2", timeout: 0}); // go to page
    await page.waitFor(5000); // give it time to load all the javascript rendered content
    const html = await page.content(); // copy page contents
    browser.close(); // close chromium
    return html // return html object
};

scrape().then((value) => {
    fs.writeFileSync("./Whosebug/page.html", value) // write the object being returned by scrape()
});

至运行 scrape_mustard.js 在 R:

library(magrittr)

system("node ./Whosebug/scrape_mustard.js")

html <- xml2::read_html("./Whosebug/page.html")

oddsMajor <- html %>% 
  rvest::html_nodes(".odds-major")

betNames <- html %>% 
  rvest::html_nodes("h3")

控制台输出：

{xml_nodeset (60)}
 [1] <span class="odds-major">2</span>
 [2] <span class="odds-major">14</span>
 [3] <span class="odds-major">15</span>
 [4] <span class="odds-major">16</span>
 [5] <span class="odds-major">17</span>
 [6] <span class="odds-major">23</span>
 [7] <span class="odds-major">25</span>
 [8] <span class="odds-major">32</span>
 [9] <span class="odds-major">33</span>
[10] <span class="odds-major">39</span>
[11] <span class="odds-major">47</span>
[12] <span class="odds-major">54</span>
[13] <span class="odds-major">55</span>
[14] <span class="odds-major">58</span>
[15] <span class="odds-major">58</span>
[16] <span class="odds-major">64</span>
[17] <span class="odds-major">73</span>
[18] <span class="odds-major">73</span>
[19] <span class="odds-major">92</span>
[20] <span class="odds-major">98</span>
...
> betNames
{xml_nodeset (60)}
 [1] <h3>Charles Howell III</h3>\n
 [2] <h3>Brian Harman</h3>\n
 [3] <h3>Austin Cook</h3>\n
 [4] <h3>J.J. Spaun</h3>\n
 [5] <h3>Webb Simpson</h3>\n
 [6] <h3>Cameron Champ</h3>\n
 [7] <h3>Peter Uihlein</h3>\n
 [8] <h3>Seung-Jae Im</h3>\n
 [9] <h3>Nick Watney</h3>\n
[10] <h3>Graeme McDowell</h3>\n
[11] <h3>Zach Johnson</h3>\n
[12] <h3>Lucas Glover</h3>\n
[13] <h3>Corey Conners</h3>\n
[14] <h3>Luke List</h3>\n
[15] <h3>David Hearn</h3>\n
[16] <h3>Adam Schenk</h3>\n
[17] <h3>Kevin Kisner</h3>\n
[18] <h3>Brian Gay</h3>\n
[19] <h3>Patton Kizzire</h3>\n
[20] <h3>Brice Garnett</h3>\n
...

我相信 phantomjs 可以做到，但我发现 puppeteer 更容易抓取 javascript 呈现的网页。还要记住 phantomjs is no longer being developed.

在 R 中抓取 Javascript 渲染的网页引用外部 javascript 脚本

Scraping Javascript-rendered webpage that references external javascript scripts in R

javascript

r

web-scraping

phantomjs