this page has been eaten

I want to programatically access the open tabs #document object by the Browser Console. I am in chrome://browser/content/browser.xhtml I fallow the docs in browser console: https://firefox-source-docs.mozilla.org/devtools-user/browser_console/index.html Following the code: var newTabBrowser = gBrowser.getBrowserForTab(gBrowser.selectedTab); newTabBrowser.addEventListener("load", function() { newTabBrowser.contentDocument.body.innerHTML = "<h1>this page has been eaten</h1>"; }, true); newTabBrowser.contentDocument.location.href = "https://mozilla.org/"; .contentDocument is null except if current tab is a page such as page about:config Is there a way to allow chrome:// tab to access read only of the tabs #documents property using the console? I understand that accessing it with javascript from the browser console would be a security issue. I want to bypass it to read, analize and compare dynamic data from the open tabs.