Run results for: for (key in obj) vs Object.keys(object)

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36

Browser: Chrome 53

Operating system: Windows

Device Platform: Other

Date tested: 8 years ago

Test name	Executions per second
for (key in obj)	517176.5 Ops/sec
Object.keys(obj)	442800.5 Ops/sec

Script Preparation code:

var obj = {};
var count = 10;
do {
    obj["key" + count + ""] = "val" + count + "";
} while(count--);

var temp = [];
for(var key in obj) {
   temp.push(obj[key]);
}

var objKey = [];
var keys = Object.keys(obj);
for(var i = 0, len = keys.length; i < len; i++) {
   objKey.push(obj[keys[i]]);
}

Tests:

for (key in obj)
var temp = []; for(var key in obj) { temp.push(obj[key]); }
Object.keys(obj)
var objKey = []; var keys = Object.keys(obj); for(var i = 0, len = keys.length; i < len; i++) { objKey.push(obj[keys[i]]); }