How to Get Extension Manifest Information

By David Walsh on July 10, 2022

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 David WalshSeptember 3, 2014

Create a CSS Flipping Animation

CSS animations are a lot of fun; the beauty of them is that through many simple properties, you can create anything from an elegant fade in to a WTF-Pixar-would-be-proud effect. One CSS effect somewhere in between is the CSS flip effect, whereby there's...

By David WalshJuly 28, 2013

Create a CSS Cube

CSS cubes really showcase what CSS has become over the years, evolving from simple color and dimension directives to a language capable of creating deep, creative visuals. Add animation and you've got something really neat. Unfortunately each CSS cube tutorial I've read is a bit...

Incredible Demos

By David WalshDecember 17, 2012

CSS calc

CSS is a complete conundrum; we all appreciate CSS because of its simplicity but always yearn for the language to do just a bit more. CSS has evolved to accommodate placeholders, animations, and even click events. One problem we always thought...

By David WalshDecember 1, 2009

Introducing MooTools ScrollSide

This post is a proof of concept post -- the functionality is yet to be perfected. Picture this: you've found yourself on a website that uses horizontal scrolling instead of vertical scrolling. It's an artistic site so you accept that the site scrolls left to right.