Puppeteer 等待所有图像加载然后截屏 [英] Puppeteer wait for all images to load then take screenshot

问题描述

我正在使用 Puppeteer 尝试在所有图片加载后截取网站的屏幕截图，但可以不让它工作.

这是我目前得到的代码，我使用的是 https://www.digg.com 作为示例网站:

const puppeteer = require('puppeteer');(异步() => {const browser = await puppeteer.launch();const page = await browser.newPage();await page.goto('https://www.digg.com/');等待 page.setViewport({width: 1640, height: 800});等待 page.evaluate(() => {返回 Promise.resolve(window.scrollTo(0,document.body.scrollHeight));});等待 page.waitFor(1000);等待 page.evaluate(() => {var images = document.querySelectorAll('img');函数预加载(){var 承诺 = [];函数加载图像(img){返回新的承诺(功能(解决，拒绝){如果(img.complete){解决(img)}img.onload = 函数(){解决(img)；};img.onerror = 函数(e){解决(img)；};})}for (var i = 0; i 

解决方案

有一个 内置选项:

await page.goto('https://www.digg.com/', {"waitUntil" : "networkidle0"});

<块引用>

networkidle0 - 当至少 500 ms 的网络连接不超过 0 个时，认为导航完成

networkidle2 - 当至少 500 毫秒的网络连接不超过 2 个时，认为导航已完成.

附言当然，如果您使用的是像 Twitter 这样无限滚动的单页应用程序，它就行不通了.

I am using Puppeteer to try to take a screenshot of a website after all images have loaded but can't get it to work.

Here is the code I've got so far, I am using https://www.digg.com as the example website:

const puppeteer = require('puppeteer');

(async () => {
    const browser = await puppeteer.launch();
    const page = await browser.newPage();
    await page.goto('https://www.digg.com/');

    await page.setViewport({width: 1640, height: 800});

    await page.evaluate(() => {
        return Promise.resolve(window.scrollTo(0,document.body.scrollHeight));
    });

    await page.waitFor(1000);

    await page.evaluate(() => {
        var images = document.querySelectorAll('img');

        function preLoad() {

            var promises = [];

            function loadImage(img) {
                return new Promise(function(resolve,reject) {
                    if (img.complete) {
                        resolve(img)
                    }
                    img.onload = function() {
                        resolve(img);
                    };
                    img.onerror = function(e) {
                        resolve(img);
                    };
                })
            }

            for (var i = 0; i < images.length; i++)
            {
                promises.push(loadImage(images[i]));
            }

            return Promise.all(promises);
        }

        return preLoad();
    });

    await page.screenshot({path: 'digg.png', fullPage: true});

    browser.close();
})();

解决方案

There is a built-in option for that:

await page.goto('https://www.digg.com/', {"waitUntil" : "networkidle0"});

networkidle0 - consider navigation to be finished when there are no more than 0 network connections for at least 500 ms

networkidle2 - consider navigation to be finished when there are no more than 2 network connections for at least 500 ms.

P.S. Of course it won't work if you're working with endless-scrolling-single-page-applications like Twitter.

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