Node.js Puppeteer如何等待page.evaluate（）方法 [英] Node.js Puppeteer How To Await For page.evaluate() Method

问题描述

我需要等待滚动操作完成然后解析。

I need to wait for scrolling action to finish, then resolve.

当我将resolve（）放在page.evaluate（）块中时，它抛出：
（节点： 22646）UnhandledPromiseRejectionWarning：错误：评估失败：ReferenceError：未定义解析

When I put resolve() inside page.evaluate() block it throws: (node:22646) UnhandledPromiseRejectionWarning: Error: Evaluation failed: ReferenceError: resolve is not defined

如果我这样保存，它将立即解决。

If I keep it like this It resolves immediately.

let scrollingPromise = new Promise((resolve, reject) => {
    page.evaluate(() => {
        const scrollingWindow = document.querySelector('.section-layout.section-scrollbox.scrollable-y.scrollable-show');            
        for (let i = 0; i < 4; i++) {
            setTimeout(function () {
                scrollingWindow.scrollBy(0, 3000);
            }, 2000 * i);
        }
    });
    resolve();
});

已解决
https://github.com/puppeteer/puppeteer/issues/844

推荐答案

我删除了for循环，不知道它的作用

I removed the for loop, don't know what it is there for

function scroll(){
    return page.evaluate(() => {
        const scrollingWindow = document.querySelector('.section-layout.section-scrollbox.scrollable-y.scrollable-show');
        return new Promise(resolve=>{
            setTimeout(function () {
                scrollingWindow.scrollBy(0, 3000);
                resolve();
            }, 2000);
        });
    });
}

这篇关于Node.js Puppeteer如何等待page.evaluate（）方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！