Optimized Fisher-Yates

JavaScript performance comparison

Test case created by Gavin Kistner

Info

Comparing a minor change to this implementation: http://stackoverflow.com/a/962890/405017

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    a = [];
    for (var i=1000;i--;) a[i]=i;
   
   
};
</script>

Test runner

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Testing in unknown unknown
Test Ops/sec
Guarded while
var tmp, current, top = a.length;

if(top) while(--top) {
  current = Math.floor(Math.random() * (top + 1));
  tmp = a[current];
  a[current] = a[top];
  a[top] = tmp;
}
 
pending…
Unguarded shift
for (var tmp, cur, top=a.length; top--;){
  cur = (Math.random() * (top + 1)) << 0;
  tmp = a[cur];
  a[cur] = a[top];
  a[top] = tmp;
}
 
pending…

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