We can now use the Performance API to compute the execution time for a piece of code in JavaScript.

//capture the start time in a variable.var timeStart = performance.now();//run a time consuming task.for (counter = 0; counter     //Do some processing   var temp = temp + counter * counter;}//capture the current timevar timeEnd = performance.now();//measure the compute timeconsole.log("Processing time is " + (timeEnd - timeStart) + " milliseconds.")