backbone.js router doesn't work on IE6

When I use the Router in Backbone.js, IE6 throw a Permission Denied on the following line:

if (this.iframe && (fr开发者_开发百科ag != this.getFragment(this.iframe.location.hash)))

the Backbone.js version is 0.5.3 , I also try some other version, but it is not work also.

As far as I know backbone.js does not claim to support IE6

The Backbone.js router does work in IE6, but it uses hash fragment routing (http://domain/#route) instead of HTML5 history push state routing (http://domain/route)