find element in obj vs array

JavaScript performance comparison

Revision 2 of this test case created

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var obj = {},
        arr = [],
        count = 0;
    for (var i = 0; i < 1000; i++) {
      arr.push(i);
      obj[i] = 1;
    }
   
   
    function in_array(needle, haystack) {
      for (var i = 0, maxi = haystack.length; i < maxi; ++i) {
        if (haystack[i] == needle) {
          return true;
        }
      }
      return false;
    }
   
    function include(needle, haystack) {
      return (haystack.indexOf(needle) != -1);
    }
};
</script>

Test runner

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

Testing in unknown unknown
Test Ops/sec
find in array (1)
if (in_array(1, arr)) {
  count++;
}
pending…
find in array (5)
if (in_array(5, arr)) {
  count++;
}
pending…
find in array (9)
if (in_array(9, arr)) {
  count++;
}
pending…
find in obj (1)
if (obj[1]) {
  count++;
}
pending…
find in obj (5)
if (obj[5]) {
  count++;
}
pending…
find in obj (9)
if (obj[9]) {
  count++;
}
pending…
indexOf in arr(1)
if (include(1, arr)) {
  count++;
}
pending…
indexOf in arr(5)
if (include(5, arr)) {
  count++;
}
pending…
indexOf in arr(9)
if (include(9, arr)) {
  count++;
}
pending…

Compare results of other browsers

Revisions

You can edit these tests or add even more tests to this page by appending /edit to the URL. Here’s a list of current revisions for this page:

2 comments

Jörn commented :

Chrome 18.0.1025 is actually Chrome Mobile (first non-beta) on a Samsung Galaxy S3

Mitch Golden commented :

I don't trust this benchmark. I am afraid that the JIT compilers are optimising the calculation by moving the entire computation outside of the loop, thereby defeating the test. The reason I think this is that (a) it's just so fast, and (b) in some cases it seems not to depend on 1 vs 5 vs 9 (and anyway all of those numbers are too small).

Add a comment