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Comment by loganlinn | Hacker News Reader

Interesting method to getting current timestamp:

  var I = +new Date;

I've always used:

  var I = (new Date).getTime();

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They're the same, +new Date doing an implicit cast to number. I prefer getTime as well for its clarity.

And another form is:

  var I = Number(new Date);

I benchmarked all the variations on Chrome, var foo = +new Date() was the fastest—not by a huge amount than the rest, but I remember there was one approach that was especially slow.

I did this while optimizing performance of a fast-paced game in Javascript (LineRage). Profiling showed that getting timestamps was responsible for significant portion of the processing time. I also ended up switching to a global clock approach.

Unfortunately I no longer have the original benchmark code/results. Would be happy to have someone replicate it.

There's also the equivalent Date.now() (as of ES5). If you'd like to write test code that overrides the current Date, this is the easiest version to override. Monkey-patching Date's constructor is a disaster. Plus, backwards compatibility can easy be added (see https://developer.mozilla.org/en/JavaScript/Reference/Global...) to non-ES5-compliant browsers.

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