There have been several important changes to JavaScript security
      in Navigator 3.0. See Chapter 20, JavaScript Security for
      complete details.
    
- 	  The Document.domain() property allows large
	  web sites that use multiple web servers to circumvent the
	  restriction that scripts from one host can't read the
	  properties of windows or documents that come from another
	  host. 
	
 
- 	  A new security model, based on data tainting, is experimental
	  in Navigator 3.0. When enabled, this new model makes
	  significant changes to the security restrictions placed on
	  JavaScript programs. It also makes new properties and array
	  elements of the History object available, and allows the
	  value property of the Password object to be
	  read. 
	
 
- 	  The taint() and
	  untaint() functions were added in Navigator
	  3.0 as part of the new data-tainting security model. The
	  taintEnabled() method of the Navigator
	  object was also added.