LCP Bookmarklet

LCP.js

javascript:
new PerformanceObserver((entryList)=>{
    for (const entry of entryList.getEntries()) {
        let consoleGroup = `%cLCP candidate: ${Math.round(entry.startTime)}ms`;
        let styles = '';
        if (entry.startTime >= 2500) {
          styles = 'color: red;';
        }
        console.group(consoleGroup, styles);
        console.log('Element:', entry.element);
        console.groupEnd(consoleGroup);
    }
}
).observe({
    type: 'largest-contentful-paint',
    buffered: true
});