CODEWITHSUNDEEP
javascriptnode.jspuppeteer
JdeMello
JdeMello

Reputation: 1718

Error: Evaluation Failed: ReferenceError: util is not defined

I am trying to pass the util module object to puppeteer page.evaluate with no success. I understand this question was asked in How to pass required module object to puppeteer page.evaluate but the solution provided does not work in my case. MWE:

const puppeteer = require("puppeteer");

const path = "http://books.toscrape.com/";

// scrape funs 
(async () =>{
    const browser = await puppeteer.launch({headless: false});
    const page = await browser.newPage();
    await page.goto(path, {waitUntil: "networkidle2", timeout: 0});
    await page.waitFor(1000);
    await page.addScriptTag({path: './node_modules/util/util.js'});
    // selector with replaceable element
    const buttonText = await page.evaluate(() => {
        let selectorButton = "#default > div > div > div > div > section > div:nth-child(2) > ol > li:nth-child(%s) > article > div.product_price > form > button";
        let buttons = [];
        for(let i = 1; i < 21; i ++){
            let textOut = document.querySelector(util.format(selectorButton, i)).innerText;
            buttons.push(textOut);
        };
        return buttons;  
    });

// return
await browse.close();
console.log(buttonText);
})();

Shows error:

UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Evaluation failed: ReferenceError: util is not defined

Thank you

Edit 1

Adding const util = require("util"); in the initial lines and doesn't work as shown in How to pass required module object to puppeteer page.evaluate.

Edit 2

Even when I use browserify I can't seem to inject the utilmodule into the puppeteer page. Steps:

On project PATH, create main.js as follows: var util = require('util');

Then on PATH in terminal: browserify main.js -o bundle.js. A file bundle.js appears in the project PATH.

Then run the following:

const puppeteer = require("puppeteer");
const path = "http://books.toscrape.com/";

// scrape funs 
(async () =>{
    const browser = await puppeteer.launch({headless: false});
    const page = await browser.newPage();
    await page.goto(path, {waitUntil: "networkidle2", timeout: 0});
    await page.waitFor(1000);
    await page.addScriptTag({path: "main.js"});
    await page.addScriptTag({path: "bundle.js"});
    // selector with replaceable element
    const buttonText = await page.evaluate(() => {
        let buttons = [];
        let selectorButton = "#default > div > div > div > div > section > div:nth-child(2) > ol > li:nth-child(%s) > article > div.product_price > form > button";
        for(let i = 1; i < 21; i ++){
            let textOut = document.querySelector(util.format(selectorButton, i)).innerText;
            buttons.push(textOut);
        };
        return buttons;  
    });

// return
await browse.close();
console.log(buttonText);
})();

Error:

UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Evaluation failed: TypeError: Cannot read property 'format' of undefined at :5:55

Upvotes: 1

Views: 6389

Answers (1)

user2652134
user2652134

Reputation:

You need to include a browser compatible build of ./node_modules/util/util.js. You can use browserify to do that or use their online service Browserify Wizard - util to download the browserified version.

Code on https://try-puppeteer.appspot.com/

const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto("http://books.toscrape.com/", {waitUntil: "networkidle2", timeout: 0});
await page.waitFor(1000);

//Copy of https://wzrd.in/standalone/util@latest
await page.addScriptTag({url: "https://cdn.rawgit.com/brahma-dev/099d0d6d43a5d013603bcd245ee7a862/raw/b0c6bb82905b5b868c287392000dc2487c41994d/util.js"});

// selector with replaceable element
const buttonText = await page.evaluate(() => {
    let buttons = [];
    let selectorButton = "#default > div > div > div > div > section > div:nth-child(2) > ol > li:nth-child(%s) > article > div.product_price > form > button";
    for(let i = 1; i < 21; i ++){
        let textOut = document.querySelector(util.format(selectorButton, i)).innerText;
        buttons.push(textOut);
    };
    return buttons;  
});

// return
await browser.close();
console.log(buttonText);

Upvotes: 2

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