Track how long (in milliseconds) a Javascript block takes to execute - using Chrome's console

console.time

// paste this in your Chrome's console to try it out, could be useful

// big loop
console.time( 'big-loop' );

var arrBig = [];
for ( var i = 0; i < 1000; i++ ) 
  arrBig.push( i );
  
console.timeEnd( 'big-loop' ); 

// small loop
console.time( 'small-loop' );

var arrSmall = [];
for ( var j = 0; j < 100; j++ )
  arrSmall.push( j );
  
console.timeEnd( 'small-loop' );