Array unshift vs prepend (v20)

Revision 20 of this benchmark created on

Preparation HTML

<script>
  var a = [];
  for(var i=0; i<6000; i++) {
    a[i] = i;
  }

  var prependArray = function(value, oldArray) {
   var i, len = oldArray.length + 1,
       newArray = new Array(len);
   newArray[0] = value;
   for (i = 0; i < len; ++i) {
    newArray.push(oldArray[i]);
   }
   return newArray;
  }
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
Unshift
a.unshift(0);
ready
Prepend function
prependArray(0, a);
ready
Unshift without mutation
a.slice(0).unshift(0);
ready
concat
var b = [0];
a = b.concat(a);
ready

Revisions

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