The fastest search ever for large amount of data http://jsperf.com/binary-search-1234

gistfile1.js

function search(arr, o) {
  var l = 0,
    u = arr.length,
    m;
  while (l <= u) {
    if (o > arr[(m = ((l + u) >> 1))]) 
      l = m + 1;
    else 
      u = (o == arr[m]) ? -2 : m - 1;
  }
  return (u == -2) ? m : -1;
}