Add a binary find to underscorejs

underscore.bfind.js

  // Binary find in a sorted array
  // val can either be a value or a function that returns
  // 1 == found, -1 for obj is less than val, 1 for obj is greater than val
  _.bfind = function(array, val) {
    if (!array.length) {
      return null;
    }
    var iterator = _.isFunction(val) ? val : function(obj) {
      return obj == val ? 0 : (obj < val ? -1 : 1);
    };
    var low = 0,
      high = array.length - 1;
    while (low < high) {
      var mid = (low + high) >> 1;
      var check = iterator(array[mid]);
      if (check === 0) {
          return array[mid];
      }
      if(check < 0) {
          if(iterator(array[high]) == 0) {
              return array[high];
          }
          low = mid + 1;
      } else {
          if(iterator(array[low]) == 0) {
              return array[low];
          }
          high = mid;
      } 
    }
    if (iterator(array[low]) === 0) {
      return array[low];
    }
    return null;
  }