For those of you not familiar with the world of web extension development, a storm is brewing with Chrome. Google will stop support for manifest version 2, which is what the vast majority of web extensions use. Manifest version 3 sees many changes but the largest change is moving from persistent background scripts to service workers. This…is…a…massive…change.
Changes from manifest version 2 to version 3 include:
- Going from persistent background script to a service worker that can die after 5 minutes
- No use of
<iframe>
elements or other DOM APIs from the service worker - All APIs have become Promise-based
- Restrictions on content from a CSP perspective
One function that web extensions often employ is executing scripts upon each new page load. For a web extension like MetaMask, we need to provide a global window.ethereum
for dApps to use. So how do we do that with manifest version 3?
As of Chrome v102, developers can define a world
property with a value of isolated
or main
(in the page) for content scripts. While developers should define content_scripts
in the extension’s manifest.json
file, the main
value really only works (due to a Chrome bug) when you programmatically define it from the service worker:
await chrome.scripting.registerContentScripts([ { id: 'inpage', matches: ['http://*/*', 'https://*/*'], js: ['in-page.js'], runAt: 'document_start', world: 'MAIN', }, ]);
In the example above, in-page.js
is injected and executed within the main content tab every time a new page is loaded. This in-page.js
file sets window.ethereum
for all dApps to use. If the world
is undefined
or isolated
, the script would still execute but would do so in an isolated environment.
Manifest version 3 work is quite the slog so please hug your closest extension developer. There are many huge structural changes and navigating those changes is a brutal push!
CSS Gradients
With CSS border-radius, I showed you how CSS can bridge the gap between design and development by adding rounded corners to elements. CSS gradients are another step in that direction. Now that CSS gradients are supported in Internet Explorer 8+, Firefox, Safari, and Chrome…
fetch API
One of the worst kept secrets about AJAX on the web is that the underlying API for it,
XMLHttpRequest
, wasn’t really made for what we’ve been using it for. We’ve done well to create elegant APIs around XHR but we know we can do better. Our effort to…
Modal-Style Text Selection with Fokus
Every once in a while I find a tiny JavaScript library that does something very specific, very well. My latest find, Fokus, is a utility that listens for text selection within the page, and when such an event occurs, shows a beautiful modal dialog in…
Select Dropdowns, MooTools, and CSS Print
I know I’ve harped on this over and over again but it’s important to enhance pages for print. You can do some things using simple CSS but today’s post features MooTools and jQuery. We’ll be taking the options of a SELECT element and generating…
Source: davidwalsh.name