substr vs regex file extension

JavaScript performance comparison

Revision 2 of this test case created

Info

For when you're testing a string for a specific filetype.

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var regex = /\.json$/i
      , filename = 'example.json';
};
</script>

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Testing in unknown unknown
Test Ops/sec
regex
( regex.test(filename) );
pending…
substr
( filename.substr(-5) === '.json' );
pending…
substr - i
( filename.toLowerCase().substr(-5) === '.json' );
pending…
charAt
var len = filename.length;
filename.charAt(len-1) === 'n' && filename.charAt(len-2) === 'o' && filename.charAt(len-3) === 's' && filename.charAt(len-4) === 'j' && filename.charAt(len-5) === '.';
pending…

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2 comments

pino commented :

( filename.toLowerCase().substr(-5) === '.json' ); what about ( filename.substr(-5).toLowerCase() === '.json' );

If you test it, test it correctly ;)

Loadx commented :

It's slower as you can see from Rev5

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