(function (factory) {
  typeof define === 'function' && define.amd ? define(factory) :
  factory();
}(function () { 'use strict';

  /**
   * Returns an array containing the initial elements which both input arrays have in common.
   *
   * A common use-case for this is discovering common ancestors between two file paths.
   *
   * ```js
   * > commonSequence = require("common-sequence");
   *
   * > pathA = "/Users/lloyd/Documents/75lb/dmd".split("/");
   * > pathB = "/Users/lloyd/Documents/75lb/array-tools".split("/");
   *
   * > commonSequence(pathA, pathB).join("/");
   * '/Users/lloyd/Documents/75lb'
   * ```
   *
   * or a more trivial example:
   * ```js
   * > a.commonSequence([ 1, 2, 3 ], [ 1, 2, 4 ])
   * [ 1, 2 ]
   * ```
   * @module common-sequence
   */
  module.exports = commonSequence;

  /**
   * Returns the initial elements which both input arrays have in common
   * @param {Array} - first array to compare
   * @param {Array} - second array to compare
   * @returns {Array}
   * @alias module:common-sequence
   */
  function commonSequence (a, b) {
    var result = [];
    for (var i = 0; i < Math.min(a.length, b.length); i++) {
      if (a[i] === b[i]) {
        result.push(a[i]);
      } else {
        break
      }
    }
    return result
  }

}));