[JAVASCRIPT] 반복문 성능 비교

Code #1
for(var i=0, len=arr.length;i<len;i++){
   arr[i]++;
}

Code #2
for(var i in arr){
   arr[i]++;
}

Code #3
var i=0, len = arr.length;
while(i<len){
  arr[i]=i;
  i++;
}

Code #4
var i=0, len = arr.length;
do{
  arr[i]=i;
  i++;
}while(i>len);