ary.js 1.17 KB
define(['../internal/createWrapper', '../internal/isIterateeCall'], function(createWrapper, isIterateeCall) {

  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
  var undefined;

  /** Used to compose bitmasks for wrapper metadata. */
  var ARY_FLAG = 128;

  /* Native method references for those with the same name as other `lodash` methods. */
  var nativeMax = Math.max;

  /**
   * Creates a function that accepts up to `n` arguments ignoring any
   * additional arguments.
   *
   * @static
   * @memberOf _
   * @category Function
   * @param {Function} func The function to cap arguments for.
   * @param {number} [n=func.length] The arity cap.
   * @param- {Object} [guard] Enables use as a callback for functions like `_.map`.
   * @returns {Function} Returns the new function.
   * @example
   *
   * _.map(['6', '8', '10'], _.ary(parseInt, 1));
   * // => [6, 8, 10]
   */
  function ary(func, n, guard) {
    if (guard && isIterateeCall(func, n, guard)) {
      n = undefined;
    }
    n = (func && n == null) ? func.length : nativeMax(+n || 0, 0);
    return createWrapper(func, ARY_FLAG, undefined, undefined, undefined, undefined, n);
  }

  return ary;
});