How to Get Extension Manifest Information

By  on  

Working on a web extension can be kinda wild -- on one side you're essentially just coding a website, on the other side you're limited to what the browser says you can do in the extension execution environment. One change in that environment is coming January 2023 -- pushing extensions to move to manifest version 3. I recently got curious about whether other popular extensions had completed the version 3 update.

Executing the following command in the background page (manifest version 2) or service worker (version 3) will provide you the extension's manifest:

chrome.runtime.getManifest()

The getManifest call returns a large object detailing the extension's manifest. Here's what you'd see for the MetaMask browser extension:

{
    "author": "https://metamask.io",
    "background": {
        "page": "background.html",
        "persistent": true
    },
    "browser_action": {
        "default_icon": {
            "16": "images/icon-16.png",
            "19": "images/icon-19.png",
            "32": "images/icon-32.png",
            "38": "images/icon-38.png",
            "64": "images/icon-64.png",
        },
        "default_popup": "popup.html",
        "default_title": "MetaMask"
    },
    "commands": {
        "_execute_browser_action": {
            "suggested_key": {
                "chromeos": "Alt+Shift+M",
                "linux": "Alt+Shift+M",
                "mac": "Alt+Shift+M",
                "windows": "Alt+Shift+M"
            }
        }
    },
    "content_scripts": [
        {
            "all_frames": true,
            "js": [
                "disable-console.js",
                "globalthis.js",
                "lockdown-install.js",
                "lockdown-run.js",
                "lockdown-more.js",
                "contentscript.js"
            ],
            "matches": [
                "file://*/*",
                "http://*/*",
                "https://*/*"
            ],
            "run_at": "document_start"
        }
    ],
    "current_locale": "en_US",
    "default_locale": "en",
    "description": "An Ethereum Wallet in your Browser",
    "externally_connectable": {
        "ids": [
            "*"
        ],
        "matches": [
            "https://metamask.io/*"
        ]
    },
    "icons": {
        "16": "images/icon-16.png",
        "19": "images/icon-19.png",
        "32": "images/icon-32.png",
        "38": "images/icon-38.png",
        "48": "images/icon-48.png",
        "64": "images/icon-64.png",
    },
    "manifest_version": 2,
    "minimum_chrome_version": "66",
    "name": "MetaMask",
    "permissions": [
        "storage",
        "unlimitedStorage",
        "clipboardWrite",
        "http://localhost:8545/",
        "https://*.infura.io/",
        "https://lattice.gridplus.io/*",
        "activeTab",
        "webRequest",
        "*://*.eth/",
        "notifications"
    ],
    "short_name": "MetaMask",
    "update_url": "https://clients2.google.com/service/update2/crx",
    "version": "10.16.1"
}

Many of web extensions are still using manifest version 2, so many extension developers are pushing to finish manifest version 3 work!

Recent Features

  • By
    How I Stopped WordPress Comment Spam

    I love almost every part of being a tech blogger:  learning, preaching, bantering, researching.  The one part about blogging that I absolutely loathe:  dealing with SPAM comments.  For the past two years, my blog has registered 8,000+ SPAM comments per day.  PER DAY.  Bloating my database...

  • By
    6 Things You Didn’t Know About Firefox OS

    Firefox OS is all over the tech news and for good reason:  Mozilla's finally given web developers the platform that they need to create apps the way they've been creating them for years -- with CSS, HTML, and JavaScript.  Firefox OS has been rapidly improving...

Incredible Demos

Discussion

  1. zakius

    Mv3 is another step in making extensions even less capable
    Chromium Mv2 and WebExtensions already barely can do anything and mostly are glorified userscripts and bookmarklets, with no persistent background pages and changed web request API it’ll only get worse

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!