Unstable
Helper functions for working with favicons.
Globals
Functions
getFavicon(object, callback)
Takes an object that represents a page's URL and returns a promise that resolves with the favicon URL for that page. The object can be a URL String or a Tab. The platform service (mozIAsyncFavicons) retrieves favicon data stored from previously visited sites, and as such, will only return favicon URLs for visited sites.
let { getFavicon } = require("sdk/places/favicon");
// String example
getFavicon("http://mozilla.org").then(function (url) {
  console.log(url); // http://mozorg.cdn.mozilla.net/media/img/favicon.ico
});
// Tab example
require("sdk/tabs").open({
  url: "http://mozilla.org",
  onReady: function (tab) {
    getFavicon(tab).then(function (url) {
      console.log(url); // http://mozorg.cdn.mozilla.net/media/img/favicon.ico
    });
  }
});
// An optional callback can be provided to handle
// the promise's resolve and reject states
getFavicon("http://mozilla.org", function (url) {
  console.log(url); // http://mozorg.cdn.mozilla.net/media/img/favicon.ico
});
Parameters
object : string|tab
 A value that represents the URL of the page to get the favicon URL from. Can be a URL String or a Tab.
callback : function
 An optional callback function that will be used in both resolve and reject cases.
Returns
promise : A promise that resolves with the favicon URL.