Array Performance

JavaScript performance comparison

Revision 8 of this test case created

Info

Manual array lookups vs. holey arrays.

Preparation code

<script>
function makeid()
{
    var text = "";
    var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

    for( var i=0; i < 10; i++ )
        text += possible.charAt(Math.floor(Math.random() * possible.length));

    return text;
}

  Benchmark.prototype.setup = function() {
var end = 1000,offset = 680;
var a1 = [],a2 = [],o={};
for(var i=0;i<end ;i++){
 if(Math.random()>0.7) {
 a1.push({id:i,name:makeid()});
 a2[i]={id:i,name:makeid()};
 o[""+i]={id:i,name:makeid()};
}
else {
 a1.push({id:i,name:makeid(),otherprop:5});
 a2[i]={id:i,name:makeid(),otherprop:5};
 o[""+i]={id:i,name:makeid(),otherprop:5};
}
}
 
  };
</script>

Test runner

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Testing in unknown unknown
Test Ops/sec
Manual Array Lookup
var id = offset;
for (var i = 0; i < a2.length; i++) {
  if (a2[i].id === id) {
    result = a2[i];
    break;
  }
}
pending…
Holey Array by Index
var id = offset;
var result = a1[id];
pending…
Object by Key
var id = '' + offset;
var result = o[id];
pending…
Object by Indexed Key
var id = offset;
var result = o[id];
pending…

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