nsIXSLTProcessor
to create an instance, use: var xsltprocessor = components.classes["@mozilla.org/document-transformer;1?type=xslt"] .createinstance(components.interfaces.nsixsltprocessor); method overview void clearparameters(); nsivariant getparameter(in domstring namespaceuri, in domstring localname); void importstylesheet(in nsidomnode style); void removeparameter(in domstring namespaceuri, in domstring localname); void reset(); void setparameter(in domstring namespaceuri, in domstring localname, in nsivariant value); nsidomdocument transformtodocument(in nsidomnode source); nsidomdocumentfragment transformtofragment(in nsidomnode source, in nsidomdocument output); methods clearparameters() removes all set parameters from this nsixsltprocessor.
... removeparameter() removes a parameter, if set.
...void removeparameter( in domstring namespaceuri, in domstring localname ); parameters namespaceuri the namespaceuri of the xslt parameter.

Migrate apps from Internet Explorer to Mozilla - Archive of obsolete content
void removeparameter(string namespaceuri, string localname) removes all set parameters from the imported xslt stylesheet and makes them default to the xslt-defined defaults.

XSLTProcessor - Web APIs
[throws] void xsltprocessor.removeparameter(string namespaceuri, string localname) removes the parameter if it was previously set.

Using the Mozilla JavaScript interface to XSL Transformations - XSLT: Extensible Stylesheet Language Transformations
setting parameters you can control parameters for the stylesheet using the xsltprocessor.setparameter(), xsltprocessor.getparameter(), and xsltprocessor.removeparameter() methods.

Setting Parameters - XSLT: Extensible Stylesheet Language Transformations
xsltprocessor provides three javascript methods to interact with these parameters: xsltprocessor.setparameter(), xsltprocessor.getparameter() and xsltprocessor.removeparameter().