Node 实现爬虫

• 以下例子的源代码：https://github.com/webxing/crawler_node

爬虫

• 按照一定的规则自动抓取网络信息的程序

反爬虫

• user-Agent，Referer，验证码
• 单位时间访问次数，访问量
• 关键信息图片混淆
• 异步加载

爬虫利器puppeteer

• 中文文档：https://zhaoqize.github.io/puppeteer-api-zh_CN/#/
• 英文文档：https://github.com/GoogleChrome/puppeteer/blob/v1.8.0/docs/api.md

截屏

• https://github.com/GoogleChrome/puppeteer
• 安装puppeteer依赖：npm i puppeteer

const puppeteer = require('puppeteer');
const { screenshot } = require('./config');
(async() => {
  const browser = await puppeteer.launch()
  const page = await browser.newPage()
  await page.goto('https://baidu.com')
  await page.screenshot({path: `${screenshot}/${Date.now()}.png`})
  await browser.close()
})()

爬取百度图片

// 获取图片
async function getImg(page, target) {
    // 重置窗口大小
    // await page.setViewport({
    //   width: 1920,
    //   height: 1080
    // })
    // console.log(chalk.green('reset viewport'))

    await page.focus('#q')
    await page.keyboard.sendCharacter(target)
    await page.click('#search')
    console.log(chalk.green('go to search list'))
  
    page.on('load', async () => {
      console.log(chalk.green('page loading done, start fetch...'))
      const imgsCounts = await page.$$eval('img.main_img', imgs => imgs.map(i => i.src))
      console.log('获取完成')
      imgsCounts.forEach( async src => {
        await src2img(src, imagesPath)
      })
    })
}

获取海词近义词

// 获取近义词
async function getWord(page, target) {
  await sleep()
  await page.focus('#q')
  await page.keyboard.type(target, {delay: 100})
  await page.click('#search')
  console.log(chalk.green('go to search list'))

  page.on('load', async () => {
    console.log(chalk.green('page loading done, start fetch...'))
    const wordsCounts = await page.$$eval('.rel .nfo li a', words => words.map(i => i.text.trim()))
    console.log(wordsCounts)
    await page.keyboard.press('Backspace')
  })
}

结语

初学node，记录之用。