gistfile1.js

var arr = [1,2,3,4,5,6,7,8,9,10],
    lim = 1000;

function iterator(sum, n) {
  return n += sum;
}

console.time(1);
for (var i=0; i<lim; i++) arr.inject(0, iterator);
console.timeEnd(1);

console.time(2);
for (var i=0; i<lim; i++) Array.reduce(arr, iterator);
console.timeEnd(2);

/*

FF 3.0.6

1: 58ms
2: 8ms

*/