perfcollector.js

Simple performance measurement tool for javascript.

Simple usage

// Initialize a performance collector, enable it.
var perfs = PerfCollector.create().enable();

// Collect statistics about the execution of stuff().
perfs.start('stuff');
stuff();
perfs.end('stuff');

perfs.logToConsole();

Alternative synthax

var timer = perfs.start('stuff');
timer.end();
// or perfs.end(timer);

Analyze the stats

PerfCollector gives access to the number of time a given timer has been called, the total time, average time and max time spent doing the action.

> perfs.stats
{ 'doStuff()': 
    { calls: 500,
      totalMs: 975,
      maxMs: 8,
      averageMs: 1.95,
      lastMs: 2 },
  'asyncLoop()': 
    { calls: 5,
      totalMs: 2967,
      maxMs: 982,
      averageMs: 593.4,
      lastMs: 982 } }

stats is a dictionnary whose key are the name of the timers, and values a set of statistics:

• calls - number of calls
• totalMs - total time spend in this timer (in millseconds)
• averageMs - average time spend in this timer (in millseconds)
• maxMs - max time spend in this timer (in millseconds)
• lastMs - time spend during the last call (in millseconds)

Disable

When PerfCollector is disabled, all function calls do pretty much nothing at all. Also note that a newly create PerfCollector is disabled by default.

To enable a PerfCollector: perf.enable() or perf.enable(true)

To disable a PerfCollector: perf.disable() or perf.enable(false)

Advanced usage

###Asynchronous functions

// Keep a reference to the timer (because maybe multiple ajaxXYZ
// are running in parralel, so it's important to know which
// one we measure).
var timer = perfs.start('ajaxXYZ');

ajaxXYZ(function () {
    // The asynchronous request is done, finish the timer
    timer.end();
});

###Name the timer at the end

// Start an anonymous timer
var timer = perfs.start();

// Perform an action
var success = doStuff();

// End the timer, give it a name depending on what happened.
if (success)
    perfs.end(timer, 'doStuff:success');
else
    perfs.end(timer, 'doStuff:error');

// Also possible to write timer.end('doStuff:success')

###Live stats

function foo () {
   
   // Start a timer
   var fooTimer = perfs.start('foo');
   
   // ... do your stuff
    
   // Stop the timer and display statistics to the console.
   fooTimer.end().logToConsole();
}

###Reuse a timer in a loop

var timer = perf.timer('syncStuff()');
for (var i = 0; i < 100; ++i) {
    timer.start();
    syncStuff();
    timer.end();
}

###Use your own time source

perf.start('stuff', myAPI.now());

// ... do your stuff

perf.end('stuff', myAPI.now());

Licence

(c) 2013, Jean-Christophe Hoelt, Fovea.cc

Jackbone is available for use under the MIT software license.