lodash/array/intersection.js

import baseIndexOf from '../internal/baseIndexOf';
import cacheIndexOf from '../internal/cacheIndexOf';
import createCache from '../internal/createCache';
import isArrayLike from '../internal/isArrayLike';

/**
 * Creates an array of unique values in all provided arrays using
 * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
 * for equality comparisons.
 *
 * @static
 * @memberOf _
 * @category Array
 * @param {...Array} [arrays] The arrays to inspect.
 * @returns {Array} Returns the new array of shared values.
 * @example
 * _.intersection([1, 2], [4, 2], [2, 1]);
 * // => [2]
 */
function intersection() {
  var args = [],
      argsIndex = -1,
      argsLength = arguments.length,
      caches = [],
      indexOf = baseIndexOf,
      isCommon = true,
      result = [];

  while (++argsIndex < argsLength) {
    var value = arguments[argsIndex];
    if (isArrayLike(value)) {
      args.push(value);
      caches.push((isCommon && value.length >= 120) ? createCache(argsIndex && value) : null);
    }
  }
  argsLength = args.length;
  if (argsLength < 2) {
    return result;
  }
  var array = args[0],
      index = -1,
      length = array ? array.length : 0,
      seen = caches[0];

  outer:
  while (++index < length) {
    value = array[index];
    if ((seen ? cacheIndexOf(seen, value) : indexOf(result, value, 0)) < 0) {
      argsIndex = argsLength;
      while (--argsIndex) {
        var cache = caches[argsIndex];
        if ((cache ? cacheIndexOf(cache, value) : indexOf(args[argsIndex], value, 0)) < 0) {
          continue outer;
        }
      }
      if (seen) {
        seen.push(value);
      }
      result.push(value);
    }
  }
  return result;
}

export default intersection;