我正在使用 Puppeteer构建一个基本的网络抓取器,到目前为止,我可以从任何给定页面返回我需要的所有数据,但是当涉及分页时,我的抓取器就会松开(只返回第一页)。
参见示例 - 这会返回前 20 本书的标题/价格,但不会查看其他 49 页的书。
只是寻找有关如何克服这个问题的指导 - 我在文档中看不到任何内容。
谢谢!
const puppeteer = require('puppeteer');
let scrape = async () => {
const browser = await puppeteer.launch({headless: false});
const page = await browser.newPage();
await page.goto('http://books.toscrape.com/');
const result = await page.evaluate(() => {
let data = [];
let elements = document.querySelectorAll('.product_pod');
for (var element of elements){
let title = element.childNodes[5].innerText;
let price = element.childNodes[7].children[0].innerText;
data.push({title, price});
}
return data;
});
browser.close();
return result;
};
scrape().then((value) => {
console.log(value);
});
要清楚。我在这里学习教程 - 此代码来自 codeburst.io 上的 Brandon Morelli!! https://codeburst.io/a-guide-to-automating-scraping-the-web-with-javascript-chrome-puppeteer-node-js-b18efb9e9921
最佳答案
我正在关注同一篇文章,以便自学如何使用 Puppeteer。 对您的问题的简短回答是,您需要再引入一个循环来遍历在线图书目录中的所有可用页面。 我已完成以下步骤以收集所有书名和价格:
- 提取的
page.evaluate
部分以 page 作为参数的单独异步函数 - 引入了带有硬编码最后目录页码的 for 循环(如果需要,您可以在 Puppeteer 的帮助下提取它)
- 将第一步中的异步函数放在循环中
与 Brandon Morelli 文章中的代码完全相同,但现在多了一个循环:
const puppeteer = require('puppeteer');
let scrape = async () => {
const browser = await puppeteer.launch({ headless: true });
const page = await browser.newPage();
await page.goto('http://books.toscrape.com/');
var results = []; // variable to hold collection of all book titles and prices
var lastPageNumber = 50; // this is hardcoded last catalogue page, you can set it dunamically if you wish
// defined simple loop to iterate over number of catalogue pages
for (let index = 0; index < lastPageNumber; index++) {
// wait 1 sec for page load
await page.waitFor(1000);
// call and wait extractedEvaluateCall and concatenate results every iteration.
// You can use results.push, but will get collection of collections at the end of iteration
results = results.concat(await extractedEvaluateCall(page));
// this is where next button on page clicked to jump to another page
if (index != lastPageNumber - 1) {
// no next button on last page
await page.click('#default > div > div > div > div > section > div:nth-child(2) > div > ul > li.next > a');
}
}
browser.close();
return results;
};
async function extractedEvaluateCall(page) {
// just extracted same exact logic in separate function
// this function should use async keyword in order to work and take page as argument
return page.evaluate(() => {
let data = [];
let elements = document.querySelectorAll('.product_pod');
for (var element of elements) {
let title = element.childNodes[5].innerText;
let price = element.childNodes[7].children[0].innerText;
data.push({ title, price });
}
return data;
});
}
scrape().then((value) => {
console.log(value);
console.log('Collection length: ' + value.length);
console.log(value[0]);
console.log(value[value.length - 1]);
});
控制台输出:
...
{ title: 'In the Country We ...', price: '£22.00' },
... 900 more items ]
Collection length: 1000
{ title: 'A Light in the ...', price: '£51.77' }
{ title: '1,000 Places to See ...', price: '£26.08' }
关于node.js - 使用 puppeteer(库)进行网页抓取时克服分页,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/52325114/