Function baseSortedIndexBy

lodash.js:4195–4236

* The base implementation of `_.sortedIndexBy` and `_.sortedLastIndexBy` * which invokes `iteratee` for `value` and each element of `array` to compute * their sort ranking. The iteratee is invoked with one argument; (value). * * @private * @param {Array} array The sorted arr

(array, value, iteratee, retHighest)

     *  into `array`.
     */
    function baseSortedIndexBy(array, value, iteratee, retHighest) {
      var low = 0,
          high = array == null ? 0 : array.length;
      if (high === 0) {
        return 0;
      }

      value = iteratee(value);
      var valIsNaN = value !== value,
          valIsNull = value === null,
          valIsSymbol = isSymbol(value),
          valIsUndefined = value === undefined;

      while (low < high) {
        var mid = nativeFloor((low + high) / 2),
            computed = iteratee(array[mid]),
            othIsDefined = computed !== undefined,
            othIsNull = computed === null,
            othIsReflexive = computed === computed,
            othIsSymbol = isSymbol(computed);

        if (valIsNaN) {
          var setLow = retHighest || othIsReflexive;
        } else if (valIsUndefined) {
          setLow = othIsReflexive && (retHighest || othIsDefined);
        } else if (valIsNull) {
          setLow = othIsReflexive && othIsDefined && (retHighest || !othIsNull);
        } else if (valIsSymbol) {
          setLow = othIsReflexive && othIsDefined && !othIsNull && (retHighest || !othIsSymbol);
        } else if (othIsNull || othIsSymbol) {
          setLow = false;
        } else {
          setLow = retHighest ? (computed <= value) : (computed < value);
        }
        if (setLow) {
          low = mid + 1;
        } else {
          high = mid;
        }
      }
      return nativeMin(high, MAX_ARRAY_INDEX);
    }

    /**
     * The base implementation of `_.sortedUniq` and `_.sortedUniqBy` without