关于puppeteer的方法$$eval里用不了nanoid生成的id？

Question

大佬们，我使用puppeteer里的方法$$eval去爬一下页面的数据，结果发现引入的nanoid不能使用，刚开始还以为是nanoid不支持commonJS写法导致的，结果调试发现在eval函数外使用可以打印成功，eval里使用就报错了
注意：$$eval返回一个promise

async callback(pg) {
        console.log(nanoid());//这里能打印出来
        const imgList = await pg.$$eval('div.swiper-wrapper>div.swiper-slide>div>img', els => els.map((el, index) => {
            return {
                imgUrl: el.src,
                alt: '图片',
                id: index,
                imgKey:nanoid()//这里不能使用nanoid
            }
        })) || []
        return imgList
    }

报的错误：

node:internal/process/promises:279
            triggerUncaughtException(err, true /* fromPromise */);
            ^

Error [ReferenceError]: nanoid is not defined
pptr:$$eval;Object.callback%20(D%3A%5C%E9%A1%B9%E7%9B%AE%5C%E7%88%AC%E8%99%AB%E7%B3%BB%E7%BB%9F%5Ccrawler%5Ccrawlers%5Cslider.js%3A8%3A34):6:24
    at $$eval ($$eval at Object.callback (D:\项目\爬虫系统\crawler\crawlers\slider.js:8:34), <anonymous>:5:23)
    at $$eval ($$eval at Object.callback (D:\项目\爬虫系统\crawler\crawlers\slider.js:8:34), <anonymous>:0:12)
    at ExecutionContext.#evaluate (D:\项目\爬虫系统\crawler\node_modules\puppeteer-core\lib\cjs\puppeteer\common\ExecutionContext.js:254:55)
    at async ExecutionContext.evaluate (D:\项目\爬虫系统\crawler\node_modules\puppeteer-core\lib\cjs\puppeteer\common\ExecutionContext.js:151:16)
    at async CDPJSHandle.evaluate (D:\项目\爬虫系统\crawler\node_modules\puppeteer-core\lib\cjs\puppeteer\common\JSHandle.js:48:16)
    at async Promise.all (index 0)
    at async CDPElementHandle.$$eval (D:\项目\爬虫系统\crawler\node_modules\puppeteer-core\lib\cjs\puppeteer\api\ElementHandle.js:227:26)
    at async Object.callback (D:\项目\爬虫系统\crawler\crawlers\slider.js:8:25)
    at async module.exports (D:\项目\爬虫系统\crawler\libs\crawler.js:10:18)

有大佬知道为什么吗

Answer 1

你这么写试试：

async callback(pg) {
        console.log(nanoid());//这里能打印出来
        const imgList = await pg.$$eval('div.swiper-wrapper>div.swiper-slide>div>img', (els,nid) => els.map((el, index) => {
            return {
                imgUrl: el.src,
                alt: '图片',
                id: index,
                imgKey:nid()//这里不能使用nanoid
            }
        }),nanoid) || []
        return imgList
    }

文档中说，要使用第三个参数传入

https://zhaoqize.github.io/puppeteer-api-zh_CN/#?product=Puppeteer&version=puppeteer-v21.2.1&show=api-pageevalselector-pagefunction-args