How to execute a javascript code in puppeteer - javascript

I'm new to puppeteer and trying to figure out how to execute a javascript code, provided as a string value, in puppeteer.
For example, the value (which is retrieved from an input) can look like this: document.getElementById('selector').value='some_value';
I've implemented the following code
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto('https://www.southwest.com/', { waitUntil: 'domcontentloaded' });
const script = await page.evaluate("document.getElementById('LandingAirBookingSearchForm_originationAirportCode').value='Dallas'; document.getElementById('LandingAirBookingSearchForm_originationAirportCode').dispatchEvent(new Event('input',{bubbles:!0}));");
await browser.close();
But it returns the following error:
Evaluation failed: TypeError: Cannot set property 'value' of null

Evaluate ur script on the page in a callback
Wait for the element with the ID of 'LandingAirBookingSearchForm_originationAirportCode' before you execute the script to be sure the side has loaded
const puppeteer = require('puppeteer');
(async function () {
const browser = await puppeteer.launch(/*{headless: false}*/);
const page = await browser.newPage();
await page.goto('https://www.southwest.com/', { waitUntil: 'domcontentloaded' });
await page.waitFor('#LandingAirBookingSearchForm_originationAirportCode');
await page.evaluate(() => {
document.getElementById('LandingAirBookingSearchForm_originationAirportCode').value='Dallas';
document.getElementById('LandingAirBookingSearchForm_originationAirportCode').dispatchEvent(new Event('input',{bubbles:!0}));
});
await browser.close();
})();

Related

puppeteer web page async code not executed

If I 'goto' a web page that contains async code, it is not executed and I don't understand why. Can anyone please help?
Node:
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto('http://127.0.0.1:8080/?code=ABC123&id=1', {
waitUntil: 'networkidle0',
});
await page.screenshot({ path: 'example.png' });
await browser.close();
})();
web page:
onmount = () => {
const params = new URLSearchParams(document.location.search);
const code = params.get('code');
// above lines are executed
// the code below is never executed
// search is an async function (not shown for brevity)
search(code).then(result => document.getElementById('title').textContent = result.title);
};
You could use page.waitForFunction to listen to the expected result of the original function. Like this, you can make sure the next step (page.screenshot) will happen only after the onmount promise is resolved in the app.
For this purpose, you could declare the value of the code= URL parameter on the top so you could compare its value later on passing it to the waitForFunction method as an argument.
await page.waitForFunction(codeValue => document.querySelector('#title').textContent == codeValue, {}, codeValue);
Example:
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
const codeValue = 'ABC123';
await page.goto(`http://127.0.0.1:8080/?code=${codeValue}&id=1`, {
waitUntil: 'networkidle0',
});
await page.waitForFunction(codeValue => document.querySelector('#title').textContent == codeValue, {}, codeValue);
await page.screenshot({ path: 'example.png' });
await browser.close();
})();

How to reload and wait for an element to appear?

I tried searching for this answer but there doesn't seem to be an answer on the Internet. What I want to do is use node js to reload a page until it finds the element with the query I want. I will be using puppeteer for other parts of the program if that will help.
Ok, I used functions from both answers and came up with this, probably unoptimized code:
const puppeteer = require("puppeteer");
(async () => {
try {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto("http://127.0.0.1:5500/main.html");
await page.waitForSelector("#buy-button");
console.log("worked");
} catch (err) {
console.log(`ERROR: ${err}`);
}
})();
But what I don't know how to do is to reload the page, and keep reloading until the id I want is there. For example, keep reloading youtube until the video you want is there(unpractical example, but I think it gets the point across).
Here's how I solved waiting for an element in puppeteer and reloading the page if it wasn't found;
async waitForSelectorWithReload(selector: string) {
const MAX_TRIES = 5;
let tries = 0;
while (tries <= MAX_TRIES) {
try {
const element = await this.page.waitForSelector(selector, {
timeout: 5000,
});
return element;
} catch (error) {
if (tries === MAX_TRIES) throw error;
tries += 1;
void this.page.reload();
await this.page.waitForNavigation({ waitUntil: 'networkidle0' });
}
}
}
And can be used as;
await waitForSelectorWithReload("input#name")
You can use "waitUntil: "networkidle2" to make sure the page is done loading. Obviously change the url, unless you are actually using evil.com
const puppeteer = require("puppeteer"); // include library
(async () =>{
const browser = await puppeteer.launch(); // run browser
const page = await browser.newPage(); // create new tab
await page.goto(
`http://www.evil.com`,
{
waitUntil: "networkidle2",
}
);
// do your stuff here
await browser.close();
})();
const puppeteer = require('puppeteer');
puppeteer.launch().then(async browser => {
const page = await browser.newPage();
page
.waitForSelector('#myId')
.then(() => console.log('got it'));
browser.close();
});

Puppeteer wait for popup page to load completely before procedding

I am trying to wait for a popup to load completely before proceeding but i am not sure how to accomplish this, currently i am using a await page.waitFor(3000);. Is there a more elegant way to do this and wait for the popup to fully load and then proceed.
below is my relevant part of the code.
await page.evaluate(async () => {
await $('#myDataExport').click();
await $('.export-btn a').click();
},);
await page.waitFor(3000);
const browserPages = await browser.pages();
const exportPopup = browserPages[browserPages.length - 1];
I have also tried to use the below
await Promise.all([
await page.click('.export-btn a'),
await page.waitForNavigation({ waitUntil: 'networkidle2' }),
]);
But I get an error Error: Node is either not visible or not an HTMLElement
Any help in this would be really great, Thanks.
I tried to make a working example. You can just ignore the request interception code.
const puppeteer = require('puppeteer')
;(async () => {
const browser = await puppeteer.launch({headless: false})
const [page] = await browser.pages()
// This network interception due to massive ads on the page
// You can remove this if you like, as this is just an example
// page.setRequestInterception(true)
// page.on('request', request => {
// if (request.url().startsWith('https://www.w3schools.com/')) {
// request.continue()
// } else {
// request.abort()
// }
// })
await page.goto('https://www.w3schools.com/tags/att_a_target.asp', {waitUntil: 'domcontentloaded'})
const [popup] = await Promise.all([
new Promise(resolve => page.on('popup', resolve)),
// THE LINES COMMENTED BELOW IS JUST AN W3SCHOOL EXAMPLE
// page.waitForSelector('a[target="_blank"].w3-btn.w3-margin-bottom'),
// page.click('a[target="_blank"].w3-btn.w3-margin-bottom'),
// YOUR CODE SHOULD LIKE THIS
page.waitForSelector('.export-btn a'),
page.click('.export-btn a'),
])
await popup.waitForSelector('#iframeResult')
await popup.screenshot({path: 'targetpopup.png'})
await popup.close()
await browser.close()
})()
Have you tried: browser.once with targetcreated target domain event?
Calling target.page() connects Puppeteer to the tab and generates a Page object.
New tabs aren't opened immediately on click. A way to await events is to create a new promise. [source]
Example:
const newPagePromise = new Promise(resolve => browser.once('targetcreated', target => resolve(target.page()));
await page.click('.export-btn a');
const newPage = await newPagePromise;

How to get all html data after all scripts and page loading is done? (puppeteer)

Finally I figured how to use Node.js. Installed all libraries/extensions. So puppeteer is working, but as it was previous with Xmlhttp... it gets only template/body of the page, without needed information. All scripts on the page engage after few second it had been opened in browser (Web app?). I need to get information inside certain tags after Whole page is loaded. Also, I would ask, if it possible to have pure JavaScript, because I do not use jQuery like code. So it doubles difficulty for me...
Here what I have so far.
const puppeteer = require('puppeteer');
const $ = require('cheerio');
let browser;
let page;
const url = "really long link with latitude and attitude";
(async () => puppeteer
.launch()
.then(await function(browser) {
return browser.newPage();
})
.then(await function(page) {
return page.goto(url).then(function() {
return page.content();
});
})
.then(await function(html) {
$('strong', html).each(function() {
console.log($(this).text());
});
})
.catch(function(err) {
//handle error
}))();
I get only template default body elements inside strong tag. But it should contain a lot more data than just 10 items.
If you want full html same as inspect? Here it is:
const puppeteer = require('puppeteer');
(async function main() {
try {
const browser = await puppeteer.launch();
const [page] = await browser.pages();
await page.goto('https://example.org/', { waitUntil: 'networkidle0' });
const data = await page.evaluate(() => document.querySelector('*').outerHTML);
console.log(data);
await browser.close();
} catch (err) {
console.error(err);
}
})();
let bodyHTML = await page.evaluate(() => document.documentElement.outerHTML);
This
Some notes:
You need not cheerio with puppeteer and you need not reparse page.content(): you already have the full DOM with all scripts run and you can evaluate any code in window context like in a browser using page.evaluate() and transferring serializable data between web API context and Node.js API context.
Try to use async/await only, this will simplify your code and flow.
If you need to wait till all the scripts and other dependencies are loaded, use waitUntil: 'networkidle0' in page.goto().
If you suspect that document scripts need some time till the needed state, use various test functions like page.waitForSelector() or fall back to page.waitFor(milliseconds).
Here is a simple script that outputs all tag names in a page.
'use strict';
const puppeteer = require('puppeteer');
(async function main() {
try {
const browser = await puppeteer.launch();
const [page] = await browser.pages();
await page.goto('https://example.org/', { waitUntil: 'networkidle0' });
const data = await page.evaluate(
() => Array.from(document.querySelectorAll('*'))
.map(elem => elem.tagName)
);
console.log(data);
await browser.close();
} catch (err) {
console.error(err);
}
})();
You can specify your task in more details and we can try to write something more appropriate.
Script for www.bezrealitky.cz (task from a comment below):
'use strict';
const fs = require('fs');
const puppeteer = require('puppeteer');
(async function main() {
try {
const browser = await puppeteer.launch();
const [page] = await browser.pages();
page.setDefaultTimeout(0);
await page.goto('https://www.bezrealitky.cz/vyhledat?offerType=pronajem&estateType=byt&disposition=&ownership=&construction=&equipped=&balcony=&order=timeOrder_desc&boundary=%5B%5B%7B%22lat%22%3A50.171436864513%2C%22lng%22%3A14.506905276796942%7D%2C%7B%22lat%22%3A50.154133576294%2C%22lng%22%3A14.599004629591036%7D%2C%7B%22lat%22%3A50.14524430128%2C%22lng%22%3A14.58773054712799%7D%2C%7B%22lat%22%3A50.129307131988%2C%22lng%22%3A14.60087568578706%7D%2C%7B%22lat%22%3A50.122604734575%2C%22lng%22%3A14.659116306376973%7D%2C%7B%22lat%22%3A50.106512499343%2C%22lng%22%3A14.657434650206028%7D%2C%7B%22lat%22%3A50.090685542974%2C%22lng%22%3A14.705099547441932%7D%2C%7B%22lat%22%3A50.072175921973%2C%22lng%22%3A14.700004206235008%7D%2C%7B%22lat%22%3A50.056898491904%2C%22lng%22%3A14.640206899053055%7D%2C%7B%22lat%22%3A50.038528576841%2C%22lng%22%3A14.666852728301023%7D%2C%7B%22lat%22%3A50.030955909657%2C%22lng%22%3A14.656128752460972%7D%2C%7B%22lat%22%3A50.013435368522%2C%22lng%22%3A14.66854956530301%7D%2C%7B%22lat%22%3A49.99444182116%2C%22lng%22%3A14.640153080292066%7D%2C%7B%22lat%22%3A50.010839032542%2C%22lng%22%3A14.527474219359988%7D%2C%7B%22lat%22%3A49.970771602447%2C%22lng%22%3A14.46224174052395%7D%2C%7B%22lat%22%3A49.970669964027%2C%22lng%22%3A14.400648545303966%7D%2C%7B%22lat%22%3A49.941901176098%2C%22lng%22%3A14.395563234671044%7D%2C%7B%22lat%22%3A49.948384148423%2C%22lng%22%3A14.337635637038034%7D%2C%7B%22lat%22%3A49.958376114735%2C%22lng%22%3A14.324977842107955%7D%2C%7B%22lat%22%3A49.9676286223%2C%22lng%22%3A14.34491711110104%7D%2C%7B%22lat%22%3A49.971859099005%2C%22lng%22%3A14.326815050839059%7D%2C%7B%22lat%22%3A49.990608728081%2C%22lng%22%3A14.342731259186962%7D%2C%7B%22lat%22%3A50.002211140429%2C%22lng%22%3A14.29483886971002%7D%2C%7B%22lat%22%3A50.023596577558%2C%22lng%22%3A14.315872285282012%7D%2C%7B%22lat%22%3A50.058309376419%2C%22lng%22%3A14.248086830069042%7D%2C%7B%22lat%22%3A50.073179111%2C%22lng%22%3A14.290193274400963%7D%2C%7B%22lat%22%3A50.102973823639%2C%22lng%22%3A14.224439442359994%7D%2C%7B%22lat%22%3A50.130060800171%2C%22lng%22%3A14.302396419107936%7D%2C%7B%22lat%22%3A50.116019827009%2C%22lng%22%3A14.360785349547996%7D%2C%7B%22lat%22%3A50.148005694843%2C%22lng%22%3A14.365662825877052%7D%2C%7B%22lat%22%3A50.14142969454%2C%22lng%22%3A14.394903042943952%7D%2C%7B%22lat%22%3A50.171436864513%2C%22lng%22%3A14.506905276796942%7D%2C%7B%22lat%22%3A50.171436864513%2C%22lng%22%3A14.506905276796942%7D%5D%5D&hasDrawnBoundary=1&mapBounds=%5B%5B%7B%22lat%22%3A50.289447077141126%2C%22lng%22%3A14.68724263943227%7D%2C%7B%22lat%22%3A50.289447077141126%2C%22lng%22%3A14.087801111111958%7D%2C%7B%22lat%22%3A50.039169221047985%2C%22lng%22%3A14.087801111111958%7D%2C%7B%22lat%22%3A50.039169221047985%2C%22lng%22%3A14.68724263943227%7D%2C%7B%22lat%22%3A50.289447077141126%2C%22lng%22%3A14.68724263943227%7D%5D%5D&center=%7B%22lat%22%3A50.16447196305031%2C%22lng%22%3A14.387521875272125%7D&zoom=11&locationInput=praha&limit=15');
await page.waitForSelector('#search-content button.btn-icon');
while (await page.$('#search-content button.btn-icon') !== null) {
const articlesForNow = (await page.$$('#search-content article')).length;
console.log(`Articles for now: ${articlesForNow}. Getting more...`);
await Promise.all([
page.evaluate(
() => { document.querySelector('#search-content button.btn-icon').click(); }
),
page.waitForFunction(
old => document.querySelectorAll('#search-content article').length > old,
{},
articlesForNow
),
]);
}
const articlesAll = (await page.$$('#search-content article')).length;
console.log(`All articles: ${articlesAll}.`);
fs.writeFileSync('full.html', await page.content());
fs.writeFileSync('articles.html', await page.evaluate(
() => document.querySelector('#search-content div.b-filter__inner').outerHTML
));
fs.writeFileSync('articles.txt', await page.evaluate(
() => [...document.querySelectorAll('#search-content article')]
.map(({ innerText }) => innerText)
.join(`\n${'-'.repeat(50)}\n`)
));
console.log('Saved.');
await browser.close();
} catch (err) {
console.error(err);
}
})();
Just one line:
const html = await page.content();
Details:
import puppeteer from 'puppeteer'
const test = async (url) => {
const browser = await puppeteer.launch({ headless: false })
const page = await browser.newPage()
await page.goto(url, { waitUntil: 'networkidle0' })
const html = await page.content()
console.log(html)
}
await test('https://stackoverflow.com/')

How to pass the "page" element to a function with puppeteer?

I’m trying check if elements are available on a page from within a function, if the element is on the page, good, continue with the code, if not, log the error.
Using the try puppeteer page, here is what I tried:
const browser = await puppeteer.launch();
const page = await browser.newPage();
const check = element => {
try {
await page.waitFor(element, {timeout: 1000});
} catch(e) {
console.log("error : ", e)
await browser.close();
}
}
await page.goto('https://www.example.com/');
check("#something");
console.log("done")
await browser.close();
I get Error running your code. SyntaxError: Unexpected identifier. I debugged a bit and it seems that page within the check function is the unexpected identifier. So I tried to pass it in with force like this:
const browser = await puppeteer.launch();
const page = await browser.newPage();
const check = (element, page) => {
try {
await page.waitFor(element, {timeout: 1000});
} catch(e) {
console.log("error : ", e)
await browser.close();
}
}
await page.goto('https://www.example.com/');
check("#something", page);
console.log("done")
await browser.close();
but I get the same Error running your code. SyntaxError: Unexpected identifier error...
What am I doing wrong?
You can use this variant to check if the element is in the page or not.
if (await page.$(selector) !== null) console.log('found');
else console.log('not found');
Now back to your code, it's throwing error because of this function is not async,
const check = async element => { // <-- make it async
try {
await page.waitFor(element, {timeout: 1000});
} catch(e) {
console.log("error : ", e)
await browser.close();
}
}
Anytime you call await, it must be inside an async function. You cannot call await everywhere. So your check function should be called like this,
await check("#something", page);
So altogether we can rewrite the code snippet this way, you can go ahead and try this one.
const browser = await puppeteer.launch();
const page = await browser.newPage();
const check = async(element, page) => (await page.$(element) !== null); // Make it async, return true if the element is visible
await page.goto('https://www.example.com/');
// now lets check for the h1 element on example.com
const foundH1 = await check("h1", page);
console.log(`Element Found? : ${foundH1}`);
// now lets check for the h2 element on example.com
const foundH2 = await check("h2", page);
console.log(`Element Found? : ${foundH2}`);
await browser.close();
Also async functions will return promises, so you have to catch that promise or use another await. Read more about async await here:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function
https://ponyfoo.com/articles/understanding-javascript-async-await

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