define(['ModernizrProto'], function(ModernizrProto) {
  /**
   * List of property values to set for css tests. See ticket #21
   * https://github.com/modernizr/modernizr/issues/21
   *
   * @memberOf Modernizr
   * @name Modernizr._prefixes
   * @optionName Modernizr._prefixes
   * @optionProp prefixes
   * @access public
   * @example
   *
   * Modernizr._prefixes is the internal list of prefixes that we test against
   * inside of things like [prefixed](#modernizr-prefixed) and [prefixedCSS](#-code-modernizr-prefixedcss). It is simply
   * an array of hyphen-case vendor prefixes you can use within your code.
   *
   * Some common use cases include
   *
   * Generating all possible prefixed version of a CSS property
   * ```js
   * var rule = Modernizr._prefixes.join('transform: rotate(20deg); ');
   *
   * rule === 'transform: rotate(20deg); webkit-transform: rotate(20deg); moz-transform: rotate(20deg); o-transform: rotate(20deg); ms-transform: rotate(20deg);'
   * ```
   *
   * Generating all possible prefixed version of a CSS value
   * ```js
   * rule = 'display:' +  Modernizr._prefixes.join('flex; display:') + 'flex';
   *
   * rule === 'display:flex; display:-webkit-flex; display:-moz-flex; display:-o-flex; display:-ms-flex; display:flex'
   * ```
   */
  // we use ['',''] rather than an empty array in order to allow a pattern of .`join()`ing prefixes to test
  // values in feature detects to continue to work
  var prefixes = (ModernizrProto._config.usePrefixes ? ' -webkit- -moz- -o- -ms- '.split(' ') : ['','']);

  // expose these for the plugin API. Look in the source for how to join() them against your input
  ModernizrProto._prefixes = prefixes;

  return prefixes;
});
