Benchmark javascript execution with callback functions

Question

I have some JavaScript that I'm trying to benchmark the time it takes to execute.

The problem with this is that the for loop completes quickly, meanwhile the execution of the Item.save() method is not yet complete.

Any suggestions how to time this that takes into account the full execution time within the contents of the loop?

Thank you!

var start = new Date().getTime();
var Item = new Item();
for (i = 0; i < 500; i++) {
  var item = {};
  item.name = 5;
  item.id = 10;
  item.set = [];
  Item.save(item, function (err, res) {
    console.log(res);
  });
}
var elapsed = new Date().getTime() - start; 
console.log(elapsed);

EDIT: This is on a nodejs server.

josh3736 · Accepted Answer · 2012-03-30 14:55:07Z

1

Just use Chrome's profiling tools. They give you total insight into exactly how much CPU time every function call on your page is taking up:

http://code.google.com/chrome/devtools/docs/cpu-profiling-files/two_profiles.png

For Node, you can try node-inspector's experimental profiler.

edited Mar 30, 2012 at 14:55

answered Mar 30, 2012 at 14:36

josh3736

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4 Comments

dzm Over a year ago

Sorry, I should have added NodeJS server.

dzm Over a year ago

Thanks, this is working well - However, it still will end the profiler mark, before all the executions have been done.

Eric Over a year ago

Chrome's profiling tools are useful for relative performance, but running with the profiler on is overall significantly slower than running with the console closed.

josh3736 Over a year ago

@Eric: Naturally, observing a system changes that system.

Joe · Accepted Answer · 2012-03-30 14:29:53Z

0

The best way to handle this would be to modify the Item.save() function to take in the start time and then do your comparison at the very end. Or, implement a callback function (succes:) on Item.save().

answered Mar 30, 2012 at 14:29

Joe

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Comments

Mathias Bynens · Accepted Answer · 2012-03-30 14:37:28Z

0

The answer is simple: create a jsPerf test case. It allows running asynchronous or “deferred” tests.

Alternatively, you could use Benchmark.js and set up a deferred test case manually.

Don’t simply compare two new Date timestamps, as that only works for synchronous tests. (Also, this is not an accurate way of measuring things across all browsers and devices.)

answered Mar 30, 2012 at 14:37

Mathias Bynens

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