var props = ['prop1', 'prop2'],i = 0;
whlie(i < props.length){
 precess(object[props[i++]]);
}

window.onload = function(){
var items = Array(1000000).join(',').split(',').map(function(item, index) {
 　　return index;
});
 console.log(forCircle())
 console.log(whileCircle())
 console.log(doCircle())
function forCircle(){
console.profile();
var currTime = new Date();
 var tal = 0;
 for(var i = 0;i < items.length; i++){
  tal = tal + process(items[i]);
 }
 console.profileEnd();
 console.log('forCircle用时：' + (new Date() - currTime) + 'ms');
 return tal;
}
function whileCircle(){
console.profile();
var currTime = new Date();
 var tal = 0;
 var j = 0;
 while (j < items.length){
  tal = tal + process(items[j++]);
 }
 console.profileEnd();
 console.log('whileCircle用时：' + (new Date() - currTime) + 'ms');
 return tal;
}
function doCircle(){
console.profile();
var currTime = new Date();
 var tal = 0;
 var k = 0;
 do{
  tal = tal + process(items[k++]);
 }while (k < items.length)
  console.profileEnd();
 console.log('doCircle用时：' + (new Date() - currTime) + 'ms');
 return tal;
}
function process(item){
 return item*100;
}
}

for(var i = 0;i < items.length; i++){
 process(items[i]);
}
//
var j = 0;
while (j < items.length){
 process(items[j++]);
}
//
var k = 0;
do{
 process(items[k++]);
}while (k < items.length)

for(var i = 0, len = items.length;i < len; i++){
 process(items[i]);
}
//
var j = 0,
count = items.length;
while (j < count){
 process(items[j++]);
}
//
var k = 0,
num = items.length;
do{
 process(items[k++]);
}while (k < num)

var iterations = Math.floor(items.length/8), 
 startAt = items.length%8, 
 i = 0; 
do{ 
 switch(startAt){ 
  case 0 : process(items[i++]); 
  case 7 : process(items[i++]); 
  case 6 : process(items[i++]); 
  case 5 : process(items[i++]); 
  case 4 : process(items[i++]); 
  case 3 : process(items[i++]); 
  case 2 : process(items[i++]); 
  case 1 : process(items[i++]); 
 } 
 startAt = 0; 
 }while(--iterations);