Question

对使用puppeteer还是陌生的，我想抓取某个网站的某些数据，但是我收到这些警告，并且控制台上没有显示任何数据。

为什么会收到以下警告，以及如何消除它们？

这是我使用的代码：

const puppeteer = require("puppeteer");

(async () => {
  // prepare for headless chrome
  const browser = await puppeteer.launch();
  const page = await browser.newPage();

  // set user agent (override the default headless User Agent)
  await page.setUserAgent(
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.129 Safari/537.36"
  );

  // go to website home page
  await page.goto("https://www.nytimes.com/");
  await page.waitForSelector("body");
  // get the User Agent on the context of Puppeteer
  const userAgent = await page.evaluate(() => navigator.userAgent);
  var rposts = await page.evaluate(() => {
    postItems = [];
    let posts = document.body.querySelectorAll(".assetWrapper");
    posts.forEach((item) => {
      try {
        title = item.querySelector("h2").innerText;
        link = item.querySelector("a").href;
        summary = item.querySelector("p").innerText;
        postItems.push({ title: title, link: link, summary: summary });
      } catch (e) {}
    });
    var items = {
      posts: postItems,
    };
    return items;
  });
  // If everything correct then no 'HeadlessChrome' sub string on userAgent
  console.log(userAgent);
  console.log(rposts);
  await browser.close();
})();

这里是越来越错误：（节点：4072）UnhandledPromiseRejectionWarning：ReferenceError：未定义浏览器（节点：15452）UnhandledPromiseRejectionWarning：ReferenceError：初始化前无法访问“页面”

Answer 1

创建无头浏览器，然后就可以使用这些代码。

#include <stdio.h>

void get_point(FILE* in)
{
  int i;
  float x, y;
  fscanf(in, "%d %f %f", &i, &x, &y);
}

void get_rectangle(FILE* in)
{
  int i;
  float a, b, c, d;
  fscanf(in, "%d %f %f %f %f", &i, &a, &b, &c, &d);
}

int main()
{
  FILE* in = stdin; // you can replace stdin with fopen to read from a file

  while (1)
  {
    switch (getc(in))
    {
    case 'P': case 'p': // follows a point
      get_point(in);
      break;
    case 'R': case 'r': // follows a rectangle
      get_rectangle(in);
      break;
    case 'Q': case 'q': // quit
      return 0;
    default: // unknown
      continue;
    }
  }
}

此致

UnhandledPromiseRejectionWarning：ReferenceError：运行操纵up时未定义浏览器？

1 个答案: