Using Puppeteer how can I get DOMContentLoaded, Load time - puppeteer

Question

Using Puppeteer how can I get DOMContentLoaded, Load time. It would be great if some once can explain how to access dev tools object, Network from Puppeteer.

Answer 1

Probably you are asking about window.performance.timing, here is a simple example how to get this data in Puppeteer:
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto('https://en.wikipedia.org');
const performanceTiming = JSON.parse(
await page.evaluate(() => JSON.stringify(window.performance.timing))
);
console.log(performanceTiming);
await browser.close();
})();
But results are quite raw and not meaningful. You should calculate the difference between each value and navigationStart, here is a full example of how to do it (code comes from this article):
const puppeteer = require('puppeteer');
const extractDataFromPerformanceTiming = (timing, ...dataNames) => {
const navigationStart = timing.navigationStart;
const extractedData = {};
dataNames.forEach(name => {
extractedData[name] = timing[name] - navigationStart;
});
return extractedData;
};
async function testPage(page) {
await page.goto('https://en.wikipedia.org');
const performanceTiming = JSON.parse(
await page.evaluate(() => JSON.stringify(window.performance.timing))
);
return extractDataFromPerformanceTiming(
performanceTiming,
'domContentLoadedEventEnd',
'loadEventEnd'
);
}
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
console.log(await testPage(page));
await browser.close();
})();