ContentIndex
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The ContentIndex
interface of the Content Index API allows developers to register their offline enabled content with the browser.
Instance properties
There are no properties of this interface.
Instance methods
ContentIndex.add()
Experimental-
Registers an item with the content index.
ContentIndex.delete()
Experimental-
Unregisters an item from the currently indexed content.
ContentIndex.getAll()
Experimental-
Returns a
Promise
that resolves with an iterable list of content index entries.
Examples
Feature detection and interface access
Here we get a reference to the ServiceWorkerRegistration
, then check for the index
property, which gives us access to the content index interface.
js
// reference registration
const registration = await navigator.serviceWorker.ready;
// feature detection
if ("index" in registration) {
// Content Index API functionality
const contentIndex = registration.index;
}
Adding to the content index
Here we're declaring an item in the correct format and creating an asynchronous function which uses the add()
method to register it with the content index.
js
// our content
const item = {
id: "post-1",
url: "/posts/amet.html",
title: "Amet consectetur adipisicing",
description:
"Repellat et quia iste possimus ducimus aliquid a aut eaque nostrum.",
icons: [
{
src: "/media/dark.png",
sizes: "128x128",
type: "image/png",
},
],
category: "article",
};
// our asynchronous function to add indexed content
async function registerContent(data) {
const registration = await navigator.serviceWorker.ready;
// feature detect Content Index
if (!registration.index) {
return;
}
// register content
try {
await registration.index.add(data);
} catch (e) {
console.log("Failed to register content: ", e.message);
}
}
Retrieving items within the current index
The below example shows an asynchronous function that retrieves items within the content index and iterates over each entry, building a list for the interface.
js
async function createReadingList() {
// access our service worker registration
const registration = await navigator.serviceWorker.ready;
// get our index entries
const entries = await registration.index.getAll();
// create a containing element
const readingListElem = document.createElement("div");
// test for entries
if (!Array.length) {
// if there are no entries, display a message
const message = document.createElement("p");
message.innerText =
"You currently have no articles saved for offline reading.";
readingListElem.append(message);
} else {
// if entries are present, display in a list of links to the content
const listElem = document.createElement("ul");
for (const entry of entries) {
const listItem = document.createElement("li");
const anchorElem = document.createElement("a");
anchorElem.innerText = entry.title;
anchorElem.setAttribute("href", entry.url);
listElem.append(listItem);
}
readingListElem.append(listElem);
}
}
Unregistering indexed content
Below is an asynchronous function, that removes an item from the content index.
js
async function unregisterContent(article) {
// reference registration
const registration = await navigator.serviceWorker.ready;
// feature detect Content Index
if (!registration.index) return;
// unregister content from index
await registration.index.delete(article.id);
}
All the above methods are available within the scope of the service worker. They are accessible from the WorkerGlobalScope.self
property:
js
// service worker script
self.registration.index.add(item);
self.registration.index.delete(item.id);
const contentIndexItems = self.registration.index.getAll();
Specifications
Specification |
---|
Content Index # content-index |
Browser compatibility
BCD tables only load in the browser