Performance check about arguments

benchmark.js

var now;
var fn, i;
var count = 10000000;

now = Date.now();
fn = function() {
  arguments[0];
}
for (i = 0; i < count; i++) {
  fn();
}
console.log('arguments[0]:\n  %d ms', Date.now() - now);

now = Date.now();
fn = function(type) {
  type;
}
for (i = 0; i < count; i++) {
  fn();
}
console.log('assigned variable:\n  %d ms', Date.now() - now);