var resources = window.performance.getEntries("resource");

var blocking = resources.filter(function(entry){
    return entry.initiatorType == 'script' || entry.initiatorType == 'link' || entry.initiatorType == 'css' ;
});

var syncronous = blocking.filter(function(entry){
	let interactive = window.performance.timing.domInteractive - window.performance.timing.fetchStart;
    return entry.startTime < interactive;
});


var maxTime = Math.max(...syncronous.map(o => o.responseEnd), 0);

console.log("DOM Interactive at: " + maxTime);