for-in versus Object.keys(..) (v24)

Revision 24 of this benchmark created on

Description

Testing if the perf hit for Object.keys(..) is enough to matter as compared to for-in.

Preparation HTML

<script>
// pre-ES5 polyfill for Object.keys()
Object.keys=Object.keys||function(o,k,r){r=[];for(k in o)r.hasOwnProperty.call(o,k)&&r.push(k);return r}

// pre-ES5 polyfill for Array.prototype.forEach()
Array.prototype.forEach||(Array.prototype.forEach=function(a,b){for(var c=0,d=this.length;d>c;++c)a.call(b,this[c],c,this)});

function iterate1(obj) {
   var ret = 0, i = 0;
   for (i in obj) {
       ret += obj[i];
   }
   return ret;
}

function iterate2(obj) {
   var ret = 0, i = 0;
   for (i in obj) {
      if(obj.hasOwnProperty(i)){
          ret += obj[i];
      }
   }
   return ret;
}

function iterate3(obj) {
   var ret = 0, i = 0;
   var keys = Object.keys(obj);
   for(var i = 0, len = keys.length; i < len; i += 1){
      ret += obj[keys[i]];
   }
}

var tmp;
</script>

Setup

tmp = "";
    
    var obj10 = {};
    var obj100 = {};
    var obj1000 = {};
    for(var i = 0; i < 1000; i++){
        if(i < 10) obj10[i] = i;
        if(i < 100) obj100[i] = i;
        if(i < 1000) obj1000[i] = i;
    }

Test runner

Ready to run.

Testing in
TestOps/sec
for-in (10)
tmp += iterate1(obj10);
ready
for-in with hasOwnProperty (10)
tmp += iterate2(obj10);
ready
Object.keys(..) (10)
tmp += iterate3(obj10);
ready
for-in (100)
tmp += iterate1(obj100);
ready
for-in with hasOwnProperty (100)
tmp += iterate2(obj100);
ready
Object.keys(..) (100)
tmp += iterate3(obj100);
ready

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.