/*!
   * dashify <https://github.com/jonschlinkert/dashify>
   *
   * Copyright (c) 2015 Jon Schlinkert.
   * Licensed under the MIT license.
   */
  
  'use strict';
  
  module.exports = function dashify(str) {
    if (typeof str !== 'string') {
      throw new TypeError('expected a string');
    }
    str = str.replace(/([a-z])([A-Z])/g, '$1-$2');
    str = str.replace(/[ \t\W]/g, '-');
    str = str.replace(/^-+|-+$/g, '');
    return str.toLowerCase();
  };