异步方法总是返回未定义

Question

I can't solve that problem so I'm asking that here:

This is the async function, and as you can see is returning an array. But it returns an undefined value.

async function scrape(pageURL) {
var dealArray = [];
try {
    const browser = await puppeteer.launch({ headless: true });
    const page = await browser.newPage();
    await page.goto(pageURL);
    await page.waitForSelector('div.s-item-container');
    const dealsElements = await page.$$('div.s-item-container');
    for(deal of dealsElements) {
        let dealTitleElement = await deal.$('div.s-item-container a.s-access-detail-page');
        let dealTitleValue = await (await dealTitleElement.getProperty('title')).jsonValue();
        let dealPriceElement= await deal.$('div.s-item-container span.a-color-price');
        let dealPriceValue = await (await dealPriceElement.getProperty('textContent')).jsonValue();
        let dealReviewsElement = await deal.$('div.s-item-container .a-icon-star');
        let dealLinkValue = await (await dealTitleElement.getProperty('href')).jsonValue() + '&tag=dragonstv-21';
        let dealReviewsClass = await (await dealReviewsElement.getProperty('className')).jsonValue();
        let dealReviewsValue;
        if(dealReviewsClass) {
            let starValue = dealReviewsClass.substring(26);
                if(starValue.indexOf('-') === -1) {
                    dealReviewsValue = starValue;
                } else {
                    let stars = starValue.replace('-', '.');
                    dealReviewsValue = stars;
                }
        }
        dealArray.push({
            "title": dealTitleValue,
            "price": dealPriceValue,
            "reviews": dealReviewsValue + "/5.0",
            "link": dealLinkValue,
            "store": "Amazon",
        });
    }
    return Promise.resolve(dealArray);
} catch(e) {
    console.error('Error: ' + e);
}
}

And here is how I'm calling it:

scrape('working link').then((data) => {
    console.log(data) // result: undefined
}

It works only if I declare the variable out of the function and the function doesn't return anything but only changes the array content.

Answer 1

As written, your function must return an array (empty or otherwise). If it's returning undefined , then you're generating an exception and should see one in the console, via your catch statement. If you're not seeing it, you might try removing the try/catch and see what exception bubbles up.

Answer 2

I've actually figured the problem out. It was returning a string so I had to use JSON.parse(request) so I have an object on which I can work on.