正确使用异步等待

Question

我正试图用木偶戏截取屏幕截图。

我对未处理的承诺拒绝错误有很多麻烦。我浏览了许多论坛和主题，提出了许多不同的内容，我申请了这些内容。

这些建议的范围从使用异步函数到使用try-catch块。

经过改进，这是我的代码的最终版本：

const puppeteer = require('puppeteer');

async function getPic() {
    const browser = await puppeteer.launch(/*{headless: false}*/);
    const page = await browser.newPage();
    page.setViewport({width: 1000, height: 500});

    process.on("unhandledRejection", (reason, p) => {
        console.error("Unhandled Rejection at: Promise", p, "reason:", reason);
        browser.close();
    });

    try{
        await page.goto('https://www.google.com');
    }
    catch (error) {
        console.log(error);
        browser.close();
    }

    await page.screenshot({path: 'pic.png'});
    await broswer.close();
}

getPic();

虽然，它仍然不起作用，我收到此错误消息：

Error: Navigation Timeout Exceeded: 30000ms exceeded
    at Promise.then (C:\...\pupet test\node_modules\pupp
eteer\lib\NavigatorWatcher.js:71:21)
    at <anonymous>
Unhandled Rejection at: Promise Promise {
  <rejected> { Error: Protocol error (Target.sendMessageToTarget): Target closed
.
    at Promise (C:\...\pupet test\node_modules\puppeteer
\lib\Connection.js:198:56)
    at new Promise (<anonymous>)
    at CDPSession.send (C:\...\pupet test\node_modules\p
uppeteer\lib\Connection.js:197:12)
    at Page._screenshotTask (C:\...\pupet test\node_modu
les\puppeteer\lib\Page.js:707:24)
    at <anonymous>
  message: 'Protocol error (Target.sendMessageToTarget): Target closed.' } } rea
son: { Error: Protocol error (Target.sendMessageToTarget): Target closed.
    at Promise (C:\...\pupet test\node_modules\puppeteer
\lib\Connection.js:198:56)
    at new Promise (<anonymous>)
    at CDPSession.send (C:\...\pupet test\node_modules\p
uppeteer\lib\Connection.js:197:12)
    at Page._screenshotTask (C:\...\pupet test\node_modu
les\puppeteer\lib\Page.js:707:24)
    at <anonymous>
  message: 'Protocol error (Target.sendMessageToTarget): Target closed.' }

Answer 1

正确使用异步等待

您需要正确使用async-await。您正在以同步方式调用异步函数。

这是经过适当等待的修改后的代码。阅读下面的代码，看看有什么不对。

const puppeteer = require('puppeteer');
async function getPic() {
    try{ // <-- wrap the whole block in try catch
      const browser = await puppeteer.launch(/*{headless: false}*/);
      const page = await browser.newPage();
      await page.setViewport({width: 1000, height: 500}); // <-- add await here so it sets viewport after it creates the page
      await page.goto('https://www.google.com');
      await page.screenshot({path: 'pic.png'});
      await broswer.close(); // <-- close browser after everything is done
    } catch (error) {
      console.log(error);
    }
}

getPic();

检查代理设置

错误表示它已超时，这意味着它甚至无法加载网站。尝试检查页面是否在浏览器上正确加载。

Puppeteer无法截取屏幕截图

1 个答案:

正确使用异步等待

检查代理设置