array-push-at-sort-position/dist/esm/index.js

Push items to an array at their correct sort-position

/**
 * copied and adapted from npm 'binary-search-insert'
 * @link https://www.npmjs.com/package/binary-search-insert
 */
export function pushAtSortPosition(array, item, compareFunction, low) {
  var length = array.length;
  var high = length - 1;

  /**
   * Optimization shortcut.
   */
  if (length === 0) {
    array.push(item);
    return 0;
  }

  /**
   * Optimization shortcut.
   * Item belongs at the end, use push() which is O(1)
   * instead of splice() which is O(n).
   */
  if (compareFunction(array[high], item) <= 0.0) {
    array.push(item);
    return length;
  }

  /**
   * Optimization shortcut.
   * Item belongs before the current low index,
   * so we can skip the binary search.
   */
  if (compareFunction(array[low], item) > 0.0) {
    array.splice(low, 0, item);
    return low;
  }
  var mid = 0;
  while (low <= high) {
    // https://github.com/darkskyapp/binary-search
    // http://googleresearch.blogspot.com/2006/06/extra-extra-read-all-about-it-nearly.html
    mid = low + (high - low >> 1);
    if (compareFunction(array[mid], item) <= 0.0) {
      // searching too low
      low = mid + 1;
    } else {
      // searching too high
      high = mid - 1;
    }
  }

  /**
   * Insert at correct position.
   * After binary search, low is the correct insertion index.
   */
  array.splice(low, 0, item);
  return low;
}