Slice vs Substr vs Substring vs [ ] Methods

JavaScript performance comparison

Revision 7 of this test case created by Aaron Patterson

Info

This is comparing the runtimes of [ ], substr, substring, and slice in a string for large (10000 character) string size.

Preparation code

<script type="text/javascript">
  var longString = "";
  // Large = 10,000
  for (var i = 0; i < 10000; i++) {
    longString += i % 10;
  }
</script>

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Testing in unknown unknown
Test Ops/sec
Substring (long)
for (i = 0; i < longString.length; i++) {
  longString.substring(i, 1);
}
pending…
Slice (long)
for (i = 0; i < longString.length; i++) {
  longString.slice(i, i + 1);
}
pending…
Substr (long)
for (i = 0; i < longString.length; i++) {
  longString.substr(i, 1);
}
pending…
[ ] (long)
for (i = 0; i < longString.length; i++) {
  longString[i];
}
pending…
charAt (long)
for (i = 0; i < longString.length; i++) {
  longString.charAt(i);
}
pending…

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