How to parse json variables on a html page with Groovy

def showMeTheJavascriptProperties() {
  def http = new HTTPBuilder( 'https://www.google.com' )
  http.request( GET, HTML ) { req ->
      uri.path = "/"
      response.success = { resp, page ->
        def properties = new Properties()
        properties.load(
          new ByteArrayInputStream(
            page.HEAD.SCRIPT.text().replace(',','').replace('"','').getBytes()
          )
        )
        println "sid: "+properties.SID      
      }
    }
  }
}