const performance = require('perf_hooks').performance;

function testLet(log) 
{	

	let counter = 0;
	let someFunc = () => counter++, sum = 0;

	for (let i = 0; i < 1000000; i++) sum += someFunc();

	// log && console.log(sum);
	return sum;
}

function testVar(log) {	
	
	var counter = 0; 	
	let someFunc = () => counter++, sum = 0;

	for (let i = 0; i < 1000000; i++) sum += someFunc();

	// log && console.log(sum);
	return sum;
}


testVar();
testLet();


let time;



time = performance.now();

testVar();

console.log('var = ', performance.now() - time);



time = performance.now();

testLet();

console.log('let = ', performance.now() - time);


// var = 18.468368001282215
// let = 40.2414800003171