Using Puppeteer & Chrome DevTools Protocol, how to get the 4 Performance Timing metrics?

Question

To create the below screenshot, I have opened the Chrome Developer Tools, selected the "Performance" tab, started a recording, opened https://www.ted.com, and then stopped the recording. This is what I see:

How can I programatically using Puppeteer & potentially the Chrome DevTools Protocol, get the 4 metrics circled in the screenshot?

Answer 1

You can try this

 const perfEntries = JSON.parse(
        await page.evaluate(() => JSON.stringify(performance.toJSON()))
    );
    const paints = await page.evaluate(_ => {
        const result = {};
        performance.getEntriesByType('paint').map(entry => {
            result[entry.name] = entry.startTime;
        });
        return result;
    });

    for (const [key, val] of Object.entries(paints)) {
        console.log(`${key}: ${Math.round(val)}ms`);
    }

    console.log('domContentLoadedEventEnd :' + `${Math.round(perfEntries.timing.domContentLoadedEventEnd) - Math.round(perfEntries.timeOrigin)}ms`);
    console.log('domComplete :' + `${ Math.round(perfEntries.timing.domComplete) - Math.round(perfEntries.timeOrigin)}ms`);
    console.log('loadEventEnd :' + `${Math.round(perfEntries.timing.loadEventEnd) - Math.round(perfEntries.timeOrigin)}ms`);

Output :

first-paint: 927ms
first-contentful-paint: 927ms
domContentLoadedEventEnd :1409ms
domComplete :4103ms
loadEventEnd :4183ms