javascript - 异步函数抛出错误，但我看不到它们

Question

我是异步函数甚至 Node.js 的新手。我正在尝试抓取一个网站并从中获取一些数据。当抓取网站时，我的代码随机抛出一个丑陋的错误:

    (node:6128) UnhandledPromiseRejectionWarning: Error: Evaluation failed: TypeError: Cannot read property 'innerText' of null
    at __puppeteer_evaluation_script__:2:75
    at ExecutionContext._evaluateInternal (c:\projects\ultipro-crawler\node_modules\puppeteer\lib\ExecutionContext.js:122:13)
    at process._tickCallback (internal/process/next_tick.js:68:7)
  -- ASYNC --
    at ExecutionContext.<anonymous> (c:\projects\ultipro-crawler\node_modules\puppeteer\lib\helper.js:111:15)
    at DOMWorld.evaluate (c:\projects\ultipro-crawler\node_modules\puppeteer\lib\DOMWorld.js:112:20)
    at process._tickCallback (internal/process/next_tick.js:68:7)
  -- ASYNC --
    at Frame.<anonymous> (c:\projects\ultipro-crawler\node_modules\puppeteer\lib\helper.js:111:15)
    at Page.evaluate (c:\projects\ultipro-crawler\node_modules\puppeteer\lib\Page.js:827:43)
    at Page.<anonymous> (c:\projects\ultipro-crawler\node_modules\puppeteer\lib\helper.js:112:23)
    at c:\projects\ultipro-crawler\phantom.js:21:30
    at process._tickCallback (internal/process/next_tick.js:68:7)
(node:6128) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:6128) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

在错误的底部，我可以看到它告诉我我有一个未经处理的 promise 拒绝，但我不知道如何更正我的代码来解决这个问题。我对使用 Promise 和异步函数不熟悉，似乎无法在这里找到一般错误。

const puppeteer = require('puppeteer');
const fs = require('fs');

(async () => {
    const browser = await puppeteer.launch();
    const page = await browser.newPage();

    const oportunities = [];
    const opportunity = {
        title: '',
        desc: '',
        category: '',
        reqName: '',
        hours: '',
        postingDate: '',
        address: ''
    };

    await page.goto('https://recruiting2.ultipro.com/PUB1004PSCU/JobBoard/d433f5c3-37c8-4bcf-a3af-248a707c7d31/?q=&o=postedDateDesc');

    const title = await page.evaluate(() => {
        return document.querySelector('.opportunity .row .col-lg-20 h3 a').innerText
    });
    const desc = await page.evaluate(() => {
        return document.querySelector('.opportunity .hidden-xs.paragraph').innerText
    });

    opportunity.title = title;
    opportunity.desc = desc;


    console.log(opportunity); 

    browser.close();
})();

Answer 1

您无法从异步 IIFE 的外部范围捕获错误。要么尝试/捕获 IIFE 中的所有代码:

(async () => {
  try {
    const browser = await puppeteer.launch();
    const page = await browser.newPage();

    const oportunities = [];
    const opportunity = {
      title: '',
      desc: '',
      category: '',
      reqName: '',
      hours: '',
      postingDate: '',
      address: ''
    };

    await page.goto('https://recruiting2.ultipro.com/PUB1004PSCU/JobBoard/d433f5c3-37c8-4bcf-a3af-248a707c7d31/?q=&o=postedDateDesc');

    const title = await page.evaluate(() => {
      return document.querySelector('.opportunity .row .col-lg-20 h3 a').innerText
    });
    const desc = await page.evaluate(() => {
      return document.querySelector('.opportunity .hidden-xs.paragraph').innerText
    });

    opportunity.title = title;
    opportunity.desc = desc;


    console.log(opportunity);

    browser.close();
  } catch (e) {
    console.error(e)
  }
})();

在顶级范围内使用 promise :

async function doJob() {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();

  const oportunities = [];
  const opportunity = {
    title: '',
    desc: '',
    category: '',
    reqName: '',
    hours: '',
    postingDate: '',
    address: ''
  };

  await page.goto('https://recruiting2.ultipro.com/PUB1004PSCU/JobBoard/d433f5c3-37c8-4bcf-a3af-248a707c7d31/?q=&o=postedDateDesc');

  const title = await page.evaluate(() => {
    return document.querySelector('.opportunity .row .col-lg-20 h3 a').innerText
  });
  const desc = await page.evaluate(() => {
    return document.querySelector('.opportunity .hidden-xs.paragraph').innerText
  });

  opportunity.title = title;
  opportunity.desc = desc;


  console.log(opportunity);

  browser.close();
}

doJob()
  .catch(console.error)

或者从另一个函数调用您的函数:

async function doJob () {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();

  const oportunities = [];
  const opportunity = {
    title: '',
    desc: '',
    category: '',
    reqName: '',
    hours: '',
    postingDate: '',
    address: ''
  };

  await page.goto('https://recruiting2.ultipro.com/PUB1004PSCU/JobBoard/d433f5c3-37c8-4bcf-a3af-248a707c7d31/?q=&o=postedDateDesc');

  const title = await page.evaluate(() => {
    return document.querySelector('.opportunity .row .col-lg-20 h3 a').innerText
  });
  const desc = await page.evaluate(() => {
    return document.querySelector('.opportunity .hidden-xs.paragraph').innerText
  });

  opportunity.title = title;
  opportunity.desc = desc;


  console.log(opportunity);

  browser.close();
}

(async () => {
  try {
    await doJob()
  } catch (err) {
    console.error(err)
  }
})()

这些是我能想到的 atm 的一些选项:)