Run results for: for-in vs Object.key

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36

Browser: Chrome 69

Operating system: Windows

Device Platform: Desktop

Date tested: 6 years ago

Test name	Executions per second
Object.keys	1379.5 Ops/sec
Object.getOwnPropertyNames	1444.5 Ops/sec
for... in...	4081.6 Ops/sec

Script Preparation code:

var objects = [];
for(var i =0;i<1000;i++){
  var object = {}; // dynamic create object, browser can't cache it
  object["p1"] = 1+i;
  object["p2"] = 2+i;
  object["p3"] = 3+i;
  object["p4"] = 4+i;
  object["p5"] = 5+i;
  object["p6"] = 6+i;
  object["p7"] = 7+i;
  object["p8"] = 8+i;
  object["p9"] = 9+i;
  objects.push(object);
}

function loop1(object){
    var keys = Object.keys(object);
    var r = 0;
    for(var i=0, len2 = keys.length;i<len2;i++){
        r += object[keys[i]];
    }
  
    return r;
}

function loop2(object){
    var keys = Object.getOwnPropertyNames(object);
    var r = 0;
    for(var i=0, len2 = keys.length;i<len2;i++){
        r += object[keys[i]];
    }
  
    return r;
}

function loop3(object){
  var r = 0;
  for(var k in object){
     r += object[k];
  }
  
  return r;
}

Tests:

Object.keys
for(var j=0,len=objects.length;j<len;j++){ loop1(objects[j]); }
Object.getOwnPropertyNames
for(var j=0,len=objects.length;j<len;j++){ loop2(objects[j]); }
for... in...
for(var j=0,len=objects.length;j<len;j++){ loop3(objects[j]); }

Run results for: for-in vs Object.key

Object.keys

Object.getOwnPropertyNames

for... in...