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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
* Collects Open Graph ( related data from a page.
export const OpenGraphPageData = {
* Collects the opengraph data from the page.
* @param {Document} document
* The document to collect from
* @returns {PageData}
collect(document) {
let pageData = {};
// Sites can technically define an Open Graph prefix other than `og:`.
// However, `og:` is one of the default RDFa prefixes and it's likely
// uncommon that sites use a custom prefix. If we find that metadata is
// missing for common sites due to this issue, we could consider adding a
// basic RDFa parser.
let openGraphTags = document.querySelectorAll("meta[property^='og:'");
for (let tag of openGraphTags) {
// Strip "og:" from the property name.
let propertyName = tag.getAttribute("property").substring(3);
switch (propertyName) {
case "description":
pageData.description = tag.getAttribute("content");
case "site_name":
pageData.siteName = tag.getAttribute("content");
case "image":
pageData.image = tag.getAttribute("content");
return pageData;