I’m attempting to capture images of a particular class several times, but I keep encountering issues with errors such as Session Closed or Terminated. Initially, I created several browser sessions to work around this issue.
Could someone provide insights on taking multiple screenshots within a single browser instance instead?
here’s my example code:
const puppeteer = require('puppeteer');
const TARGET_CLASS = '.icon';
(async () => {
let count = 0;
async function takeScreenshots() {
const browser = await puppeteer.launch({ headless: true });
try {
const page = await browser.newPage();
page.setViewport({ width: 1024, height: 768, deviceScaleFactor: 2 });
await page.goto('https://example.com/');
await page.waitForTimeout(1000);
const dimensions = await page.evaluate(selector => {
const element = document.querySelector(selector);
const { x, y, width, height } = element.getBoundingClientRect();
return { left: x, top: y, width, height, id: element.id };
}, TARGET_CLASS);
await page.screenshot({
path: `snapshot-${count}.png`,
clip: { x: dimensions.left, y: dimensions.top, width: dimensions.width, height: dimensions.height }
});
count++;
} catch (error) {
console.error(error);
} finally {
await browser.close();
}
}
async function initiate() {
await takeScreenshots();
setTimeout(initiate, 200);
}
initiate();
})();
To take multiple screenshots in a single Puppeteer session, move the browser launch and close outside the loop. This way, the browser instance stays open. Here's your updated code:
const puppeteer = require('puppeteer');
const TARGET_CLASS = '.icon';
(async () => {
let count = 0;
const browser = await puppeteer.launch({ headless: true });
async function takeScreenshots() {
try {
const page = await browser.newPage();
page.setViewport({ width: 1024, height: 768, deviceScaleFactor: 2 });
await page.goto('https://example.com/');
await page.waitForTimeout(1000);
const dimensions = await page.evaluate(selector => {
const element = document.querySelector(selector);
const { x, y, width, height } = element.getBoundingClientRect();
return { left: x, top: y, width, height };
}, TARGET_CLASS);
await page.screenshot({
path: `snapshot-${count}.png`,
clip: { x: dimensions.left, y: dimensions.top, width: dimensions.width, height: dimensions.height }
});
count++;
await page.close();
} catch (error) {
console.error(error);
}
}
async function initiate() {
await takeScreenshots();
setTimeout(initiate, 200);
}
initiate();
})();
Place the await browser.close() after completing all screenshots outside the loop if needed.
In addition to moving the browser launch outside the loop as suggested, it's imperative to consider optimization options to enhance efficiency in taking multiple screenshots within a single session. Here’s a refined approach that keeps the browser and page instances open, allowing you to adjust the target pages and capture multiple shots reliably.
const puppeteer = require('puppeteer');
const TARGET_CLASS = '.icon';
const URLS = [
'https://example.com/page1',
'https://example.com/page2',
'https://example.com/page3',
]; // Add more URLs as needed
(async () => {
let count = 0;
const browser = await puppeteer.launch({ headless: true });
const page = await browser.newPage();
page.setViewport({ width: 1024, height: 768, deviceScaleFactor: 2 });
async function takeScreenshots(url) {
try {
await page.goto(url);
await page.waitForSelector(TARGET_CLASS);
const dimensions = await page.evaluate(selector => {
const element = document.querySelector(selector);
const { x, y, width, height } = element.getBoundingClientRect();
return { left: x, top: y, width, height };
}, TARGET_CLASS);
await page.screenshot({
path: `snapshot-${count}.png`,
clip: { x: dimensions.left, y: dimensions.top, width: dimensions.width, height: dimensions.height }
});
count++;
} catch (error) {
console.error('Error capturing screenshot:', error);
}
}
for (const url of URLS) {
await takeScreenshots(url);
}
await browser.close();
})();
This modified approach iterates through an array of URLs, capturing screenshots of the specified class within a single browser instance. Keeping the browser and page open reduces session management overhead and prevents errors associated with frequent launches and closures. Additionally, using waitForSelector improves reliability by ensuring the target element is ready before attempting to capture it.
To effectively take multiple screenshots within a single browser session using Puppeteer, streamline your approach by retaining the browser instance open throughout your process. This not only resolves common errors like Session Closed or Terminated but also optimizes performance by minimizing repeated resource-intensive browser launches. Here's a practical method that focuses on efficiency:
const puppeteer = require('puppeteer');
const TARGET_CLASS = '.icon';
(async () => {
let count = 0;
const browser = await puppeteer.launch({ headless: true });
async function takeScreenshots() {
const page = await browser.newPage();
try {
page.setViewport({ width: 1024, height: 768, deviceScaleFactor: 2 });
await page.goto('https://example.com/');
await page.waitForSelector(TARGET_CLASS);
const dimensions = await page.evaluate(selector => {
const element = document.querySelector(selector);
const { x, y, width, height } = element.getBoundingClientRect();
return { left: x, top: y, width, height };
}, TARGET_CLASS);
await page.screenshot({
path: `snapshot-${count}.png`,
clip: { x: dimensions.left, y: dimensions.top, width: dimensions.width, height: dimensions.height }
});
count++;
await page.close();
} catch (error) {
console.error('Failed to capture screenshot:', error);
}
}
for (let i = 0; i < 5; i++) { // Adjust for the number of screenshots
await takeScreenshots();
await new Promise(resolve => setTimeout(resolve, 200));
}
await browser.close();
})();
This code keeps the browser open and only closes it after capturing all required screenshots. By using a simple loop and introducing delays with setTimeout, you manage the sequence without overwhelming processes.
To streamline your approach using Puppeteer for taking multiple screenshots within a single browser session, keeping the browser instance open is indeed crucial, as discussed by others. However, let's add a unique perspective by leveraging Puppeteer's Promise.all to handle concurrent page operations efficiently. This can be particularly useful if you need to deal with multiple instances or pages in parallel, thus increasing the performance and responsiveness of your application.
const puppeteer = require('puppeteer');
const TARGET_CLASS = '.icon';
const URLS = [
'https://example.com/page1',
'https://example.com/page2',
'https://example.com/page3',
]; // Expand this list with your URLs
(async () => {
const browser = await puppeteer.launch({ headless: true });
const pagePromises = URLS.map(async (url, index) => {
const page = await browser.newPage();
try {
await page.setViewport({ width: 1024, height: 768, deviceScaleFactor: 2 });
await page.goto(url);
await page.waitForSelector(TARGET_CLASS);
const dimensions = await page.evaluate(selector => {
const element = document.querySelector(selector);
const { x, y, width, height } = element.getBoundingClientRect();
return { left: x, top: y, width, height };
}, TARGET_CLASS);
await page.screenshot({
path: `snapshot-${index}.png`,
clip: { x: dimensions.left, y: dimensions.top, width: dimensions.width, height: dimensions.height }
});
} catch (error) {
console.error(`Error capturing screenshot for ${url}:`, error);
} finally {
await page.close();
}
});
await Promise.all(pagePromises);
await browser.close();
})();
In this example, Promise.all is used to handle multiple asynchronous page operations concurrently. This not only keeps the browser open for the entire session but also handles multiple pages or instances simultaneously. This approach can significantly enhance your workflow if capturing screenshots from multiple URLs in parallel suits your needs. Remember to have appropriate error handling in place to catch and display any errors while processing each page to debug easier.