/* 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
http://mozilla.org/MPL/2.0/. */
import { PageDataSchema } from "resource:///modules/pagedata/PageDataSchema.sys.mjs";
/**
* Represents an item from the schema.org specification.
*
* Every `Item` has a type and a set of properties. Each property has a string
* name and a list of values. It often isn't clear from the spec whether a
* property is expected to have a list of values or just one value so this
* data structure stores every property as a list and provides a simple method
* to get the first property value.
*/
class Item {
/** @type {string} The type of the item e.g. "Product" or "Person". */
type;
/** @type {Map<string, any[]>} Properties of the item. */
properties = new Map();
/**
* Constructors a new `Item` of the given type.
*
* @param {string} type
* The type of the item.
*/
constructor(type) {
this.type = type;
}
/**
* Tests whether a property has any values in this item.
*
* @param {string} prop
* The name of the property.
* @returns {boolean}
*/
has(prop) {
return this.properties.has(prop);
}
/**
* Gets all of the values for a property. This may return an empty array if
* there are no values.
*
* @param {string} prop
* The name of the property.
* @returns {any[]}
*/
all(prop) {
return this.properties.get(prop) ?? [];
}
/**
* Gets the first value for a property.
*
* @param {string} prop
* The name of the property.
* @returns {any}
*/
get(prop) {
return this.properties.get(prop)?.[0];
}
/**
* Sets a value for a property.
*
* @param {string} prop
* The name of the property.
* @param {any} value
* The value of the property.
*/
set(prop, value) {
let props = this.properties.get(prop);
if (props === undefined) {
props = [];
this.properties.set(prop, props);
}
props.push(value);
}
/**
* Converts this item to JSON-LD.
*
* Single array properties are converted into simple properties.
*
* @returns {object}
*/
toJsonLD() {
/**
* Converts a value to its JSON-LD representation.
*
* @param {any} val
* The value to convert.
* @returns {any}
*/
function toLD(val) {
if (val instanceof Item) {
return val.toJsonLD();
}
return val;
}
let props = Array.from(this.properties, ([key, value]) => {
if (value.length == 1) {
return [key, toLD(value[0])];
}
return [key, value.map(toLD)];
});
return {
"@type": this.type,
...Object.fromEntries(props),
};
}
}
/**
* Parses the value for a given microdata property.
* See
https://html.spec.whatwg.org/multipage/microdata.html#values for the parsing spe
c
*
* @param {Element} propElement
* The property element.
* @returns {any}
* The value of the property.
*/
function parseMicrodataProp(propElement) {
if (propElement.hasAttribute("itemscope")) {
throw new Error(
"Cannot parse a simple property value from an itemscope element."
);
}
const parseUrl = (urlElement, attr) => {
if (!urlElement.hasAttribute(attr)) {
return "";
}
try {
let url = new URL(
urlElement.getAttribute(attr),
urlElement.ownerDocument.documentURI
);
return url.toString();
} catch (e) {
return "";
}
};
switch (propElement.localName) {
case "meta":
return propElement.getAttribute("content") ?? "";
case "audio":
case "embed":
case "iframe":
case "source":
case "track":
case "video":
return parseUrl(propElement, "src");
case "img":
// Some pages may be using a lazy loading approach to images, putting a
// temporary image in "src" while the real image is in a differently
// named attribute. So far we found "content" and "data-src" are common
// names for that attribute.
return (
parseUrl(propElement, "content") ||
parseUrl(propElement, "data-src") ||
parseUrl(propElement, "src")
);
case "object":
return parseUrl(propElement, "data");
case "a":
case "area":
case "link":
return parseUrl(propElement, "href");
case "data":
case "meter":
return propElement.getAttribute("value");
case "time":
if (propElement.hasAtribute("datetime")) {
return propElement.getAttribute("datetime");
}
return propElement.textContent;
default:
// Not mentioned in the spec but sites seem to use it.
if (propElement.hasAttribute("content")) {
return propElement.getAttribute("content");
}
return propElement.textContent;
}
}
/**
* Collects product data from an item.
*
* @param {Document} document
* The document the item comes from.
* @param {PageData} pageData
* The pageData object to add to.
* @param {Item} item
* The product item.
*/
function collectProduct(document, pageData, item) {
if (item.has("image")) {
let url = new URL(item.get("image"), document.documentURI);
pageData.image = url.toString();
}
if (item.has("description")) {
pageData.description = item.get("description");
}
pageData.data[PageDataSchema.DATA_TYPE.PRODUCT] = {
name: item.get("name"),
};
for (let offer of item.all("offers")) {
if (!(offer instanceof Item) || offer.type != "Offer") {
continue;
}
let price = parseFloat(offer.get("price"));
if (!isNaN(price)) {
pageData.data[PageDataSchema.DATA_TYPE.PRODUCT].price = {
value: price,
currency: offer.get("priceCurrency"),
};
break;
}
}
}
/**
* Returns the root microdata items from the given document.
*
* @param {Document} document
* The DOM document to collect from.
* @returns {Item[]}
*/
function collectMicrodataItems(document) {
// First find all of the items in the document.
let itemElements = document.querySelectorAll(
"[itemscope][itemtype^='https://schema.org/'], [itemscope][itemtype^='http://schema.org/']"
);
/**
* Maps elements to the closest item.
*
* @type {Map<Element, Item>}
*/
let items = new Map();
/**
* Finds the item for an element. Throws if there is no item. Caches the
* result.
*
* @param {Element} element
* The element to search from.
* @returns {Item}
*/
function itemFor(element) {
let item = items.get(element);
if (item) {
return item;
}
if (!element.parentElement) {
throw new Error("Element has no parent item.");
}
item = itemFor(element.parentElement);
items.set(element, item);
return item;
}
for (let element of itemElements) {
let itemType = element.getAttribute("itemtype");
// Strip off the base url
if (itemType.startsWith("https://")) {
itemType = itemType.substring(19);
} else {
itemType = itemType.substring(18);
}
items.set(element, new Item(itemType));
}
// The initial roots are just all the items.
let roots = new Set(items.values());
// Now find all item properties.
let itemProps = document.querySelectorAll(
"[itemscope][itemtype^='https://schema.org/'] [itemprop], [itemscope][itemtype^='http://schema.org/'] [itemprop]"
);
for (let element of itemProps) {
// The item is always defined above the current element.
let item = itemFor(element.parentElement);
// The properties value is either a nested item or a simple value.
let propValue = items.get(element) ?? parseMicrodataProp(element);
item.set(element.getAttribute("itemprop"), propValue);
if (propValue instanceof Item) {
// This item belongs to another item and so is not a root item.
roots.delete(propValue);
}
}
return [...roots];
}
/**
* Returns the root JSON-LD items from the given document.
*
* @param {Document} document
* The DOM document to collect from.
* @returns {Item[]}
*/
function collectJsonLDItems(document) {
/**
* The root items.
*
* @type {Item[]}
*/
let items = [];
/**
* Converts a JSON-LD value into an Item if appropriate.
*
* @param {any} val
* The value to convert.
* @returns {any}
*/
function fromLD(val) {
if (typeof val == "object" && "@type" in val) {
let item = new Item(val["@type"]);
for (let [prop, value] of Object.entries(val)) {
// Ignore meta properties.
if (prop.startsWith("@")) {
continue;
}
if (!Array.isArray(value)) {
value = [value];
}
item.properties.set(prop, value.map(fromLD));
}
return item;
}
return val;
}
let scripts = document.querySelectorAll("script[type='application/ld+json'");
for (let script of scripts) {
try {
let content = JSON.parse(script.textContent);
if (typeof content != "object") {
continue;
}
if (!("@context" in content)) {
continue;
}
if (
content["@context"] != "http://schema.org" &&
content["@context"] != "https://schema.org"
) {
continue;
}
let item = fromLD(content);
if (item instanceof Item) {
items.push(item);
}
} catch (e) {
// Unparsable content.
}
}
return items;
}
/**
* Collects schema.org related data from a page.
*
* Currently only supports HTML Microdata and JSON-LD formats, not RDFa.
*/
export const SchemaOrgPageData = {
/**
* Parses and collects the schema.org items from the given document.
* The returned items are the roots, i.e. the top-level items, there may be
* other items as nested properties.
*
* @param {Document} document
* The DOM document to parse.
* @returns {Item[]}
*/
collectItems(document) {
return collectMicrodataItems(document).concat(collectJsonLDItems(document));
},
/**
* Performs PageData collection from the given document.
*
* @param {Document} document
* The DOM document to collect from.
* @returns {PageData}
*/
collect(document) {
let pageData = { data: {} };
let items = this.collectItems(document);
for (let item of items) {
switch (item.type) {
case "Product":
if (!(PageDataSchema.DATA_TYPE.PRODUCT in pageData.data)) {
collectProduct(document, pageData, item);
}
break;
case "Organization":
pageData.siteName = item.get("name");
break;
}
}
return pageData;
},
};
