javascript - 来自 Promise Async 的带有 puppeteer 错误的 NodeJS
问题描述
我正在使用 NodeJS 开发社区自动屏幕捕获应用程序。实际上,它与它的屏幕捕获功能配合得很好当我等待一段时间时,它似乎有一个错误并且不再工作了。
我在控制台中发现了这样的错误消息。
(node:23436) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'screenshot' of null
at C:\Users\user\Downloads\Projects\Bander-Statistics\google.js:60:31
at process._tickCallback (internal/process/next_tick.js:68:7)
(node:23436) 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:23436) [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.
same data
我认为问题出在异步功能上。但是我必须等待很长时间才能再次看到错误消息,我不知道为什么会这样。
这是我的完整代码
const puppeteer = require('puppeteer');
const cheerio = require('cheerio')
const request = require('request');
let postArray = [];
let uniq = [];
let initNumber;
let prevNumber;
function data() {
(async () => {
await request.get({
url: 'https://www.clien.net/service/group/community'
}, function (err, response, body) {
if (err) {
throw err;
}
let $ = cheerio.load(body);
initNumber = $('.list_item.symph_row').attr('data-board-sn');
})
if (initNumber === prevNumber) {
console.log('same data'); // Same Data, Do nothing
// prevNumber = initNumber; // Compare with prevNumber
} else {
postArray.push(initNumber); // Different Data put to Array
console.log(postArray);
prevNumber = initNumber; // Compare with prevNumber
}
uniq = postArray.reduce(function (a, b) { // Sometimes in postArray have duplicate value so remove it.
if (a.indexOf(b) < 0) a.push(b);
return a;
}, []);
console.log(uniq);
})()
}
setInterval(data, 1000); // Interval 1 second because new post's are really uploaded fast
// screenshot function
function screenshot() {
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
// Adjustments particular to this page to ensure we hit desktop breakpoint.
await page.setViewport({
width: 1920,
height: 100000,
deviceScaleFactor: 1
});
if (uniq.length === 0) { // If postArray are 0, Do nothing
console.log(`This time Array ${uniq.length}`)
console.log('No Processing this time');
} else {
for (let i = 0; i < uniq.length; i++) { //If postArray have value iterate all value to screenshot
await page.goto(`https://www.clien.net/service/board/park/${uniq[i]}`);
const overlay = await page.$('.post_view');
await overlay.screenshot({
path: `./image/${uniq[i]}.png`, // save file name with postarray value
}).catch((err) => console.log(`Processing Image Clear Array INIT again ${err}`)) // Browser Close)
}
postArray = []; // Reset Array
await browser.close();
}
postArray = []; // Reset Array
await browser.close(); // Browser Close
})();
}
setInterval(screenshot, 30000); // Interval 10 seconds
解决方案
我敢打赌,问题是您无法获得.post_view
. 这就是为什么它是空的。你可以尝试waitForSelector
在那里使用。
await page.goto(`https://www.clien.net/service/board/park/${uniq[i]}`);
const overlay = await page.waitForSelector('.post_view').catch((err) => console.log('Unable to get a post_view element'));
if (overlay)
await overlay.screenshot({
path: `./image/${uniq[i]}.png`, // save file name with postarray value
}).catch((err) => console.log(`Processing Image Clear Array INIT again ${err}`)) // Browser Close)
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