code: function capitalize(str) {
    return str.replace(STRING_CAPITALIZE_REGEXP, (match, separator, chr) => match.toUpperCase());
  }
docs: Returns the Capitalized form of a string
  ```javascript
  'innerHTML'.capitalize()         // 'InnerHTML'
  'action_name'.capitalize()       // 'Action_name'
  'css-class-name'.capitalize()    // 'Css-class-name'
  'my favorite items'.capitalize() // 'My favorite items'
  'privateDocs/ownerInvoice'.capitalize(); // 'PrivateDocs/ownerInvoice'
  ```
  @method capitalize
  @param {String} str The string to capitalize.
  @return {String} The capitalized string.