I'll preface this with I'm still quite fresh to coding and am still learning,

I am attempting to execute a script that uses two async functions with node.js. The first function uses puppeteer to fetch links from a webpage and the second uses googleapi to log that data into a google sheet.

Issue I'm running into is the array I'm fetching from the first function is coming up as undefined for the second.

I believe it's an issue of the second script being executed before the first is complete and can return the data. Any insight or help will be much appreciated.

const puppeteer = require('puppeteer')

async function scrapeProduct(url) {
    const browser = await puppeteer.launch({
        headless: false
    });
    
    const page = await browser.newPage();
    await page.goto(url);

    const grablinks = await page.evaluate(() => {
          //retrieves links
            
    }); 

    await browser.close();
    
    return grabLinks;    
}
const {google} = require('googleapis')
const credentials = require('')

const client = new google.auth.JWT(
    credentials.client_email, 
    null, 
    credentials.private_key, 
    ['https://www.googleapis.com/auth/spreadsheets']
);


client.authorize(function(err,tokens){
    if (err){
        console.log(err);
        return;
    } else{
        console.log('Connected!');
        gsrun(client);
    }

});
async function gsrun(cl){
    
    const gsapi = google.sheets({version: 'v4', auth: cl});

    const updateOptions = {
        spreadsheetId: '',
        range: '',
        valueInputOption: 'USER_ENTERED',
        resource: { values :grabLinks}
    };

    let res = await gsapi.spreadsheets.values.update(updateOptions);

}

CodePudding user response：

1. Please, learn more about Scopes.

2. Your function scrapeProduct never executes.

Change your gsrun function to this:

async function gsrun(cl,url){
    
    const gsapi = google.sheets({version: 'v4', auth: cl});
    let grabLinks = await scrapeProduct(url);
    const updateOptions = {
        spreadsheetId: '',
        range: '',
        valueInputOption: 'USER_ENTERED',
        resource: { values :grabLinks}
    };

    let res = await gsapi.spreadsheets.values.update(updateOptions);

}

And then run gsrun with client and your needed url inside client.authorize's callback as your wrote.

CodePudding user response：

First, you've only defined scrapeProduct and aren't calling it:

async function gsrun(cl){
    const gsapi = google.sheets({version: 'v4', auth: cl});

    const grabLinks = await scrapeProduct(url); // <--- This

    const updateOptions = {
        spreadsheetId: '',
        range: '',
        valueInputOption: 'USER_ENTERED',
        resource: { values: grabLinks}
    };
    let res = await gsapi.spreadsheets.values.update(updateOptions);
}

However, this will still error out. This is because you've defined scrapeProduct to be asynchronous (and await won't work because scrapeProduct isn't returning a promise) so updateOptions.resource will have the undefined value.

You can fix this by making sure scrapeProduct returns a promise:

function scrapeProduct(url) {
    return new Promise(async(resolve, reject) => {
        const browser = await puppeteer.launch({
            headless: false
        });
    
        const page = await browser.newPage();
        await page.goto(url);

        const grablinks = await page.evaluate(() => {
              //retrieves links
            
        }); 

        await browser.close();
    
        resolve(grabLinks);
    }); 
}

Now, calling await scrapeProduct(url) inside gsrun() will work as the code won't execute further until grabLinks is returned from scrapeProduct