Info

Looking for elements at the very start of the array gives a false impression, see how the picture changes if they elements are at the end of the array.

But how long does it take to build and object lookup table?

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.

if (in_array(1, arr)) {
  count++;
}

if (in_array(500, arr)) {
  count++;
}

if (in_array(999, arr)) {
  count++;
}

if (obj[1]) {
  count++;
}

if (obj[500]) {
  count++;
}

if (obj[999]) {
  count++;
}

if (arr.indexOf(1) != -1) {
  count++;
}

if (arr.indexOf(500) != -1) {
  count++;
}

if (arr.indexOf(999) != -1) {
  count++;
}

for (var i = 0; i < 1000; i++) {
  obj[i] = arr[i];
}

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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:

• Revision 1: published on 1st July 2012
• Revision 2: published on 2nd July 2012
• Revision 3: published on 1st August 2012
• Revision 4: published by Rob Edgar on 27th September 2012

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