console: timeEnd() method

label Optional

A string representing the name of the timer to stop. Once stopped, the elapsed time is automatically displayed in the Web console along with an indicator that the time has ended. If omitted, the label "default" is used.

None (undefined).

console.time("answer time");
alert("Click to continue");
console.timeLog("answer time");
alert("Do a bunch of other stuff…");
console.timeEnd("answer time");

The output from the example above shows the time taken by the user to dismiss the first alert box, followed by the cumulative time it took for the user to dismiss both alerts:

Notice that the timer's name is displayed when the timer value is logged using timeLog() and again when it's stopped. In addition, the call to timeEnd() has the additional information, "timer ended" to make it obvious that the timer is no longer tracking time.