Character counting

JavaScript performance comparison

Test case created by Jared Wein

Preparation code

 
<script>
  Benchmark.prototype.setup = function() {
    var s = "http://msujaws.wordpress.com/2012/09/18/unnecessary-regular-expressions/#comments";
  };
</script>

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Testing in unknown unknown
Test Ops/sec
Regex character counting
 
var t = s.replace(/[^.]*/g, "").length;
 pending…
Iterative character counting
 
var j, l = s.length, count = 0;
for (j = 0; j < l; j++) {
  if (s[j] == '.')
    count++;
}
 pending…
Iterative character counting (no coercion)
 
var j, l = s.length, count = 0;
for (j = 0; j < l; j++) {
  if (s[j] === '.')
    count++;
}
 pending…
Iterative character counting (prefix increment)
 
var j, l = s.length, count = 0;
for (j = 0; j < l; ++j) {
  if (s[j] == '.')
    ++count;
}
 pending…

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