key vs var key in loop

Benchmark created on

Preparation HTML

<script>
  var obj={};
  for(var i=0;i<1000;++i){
     obj['key'+i]=true;
  }
</script>

Test runner

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Testing in
TestOps/sec
for(key in obj)
var key;
for(key in obj){
   obj[key]=obj[key];
}
ready
for(var key in obj)
for(var key in obj){
   obj[key]=obj[key];
}
ready

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