const t0 = performance.now();
for (let i = 0; i < array.length; i++) 
{
    
    
  // some code
}
const t1 = performance.now();
console.log(t1 - t0, 'milliseconds');

console.time('test');
for (let i = 0; i < array.length; i++) {
    
    
  // some code
}
console.timeEnd('test');