FID Bookmarklet

FID.js

javascript:
new PerformanceObserver((entryList)=>{
    for (const entry of entryList.getEntries()) {
        const delay = entry.processingStart - entry.startTime;
        let consoleGroup = `%cFID value: ${Math.round(delay)}ms`;
        let styles = '';
        if (delay >= 100) {
          styles = 'color: red;';
        }
        console.group(consoleGroup, styles);
        console.log(`Event name: ${entry.name}`);
        console.log('Element:', entry.target);
        console.groupEnd(consoleGroup);
    }
}
).observe({
    type: 'first-input',
    buffered: true
});