Can JavaScript Check Chrome Extension Installation?

In today's web development, it may be necessary to determine if a specific Chrome extension is installed on a user's browser. This functionality enables web applications to seamlessly interact with installed browser extensions.

Extension Background Script:

To enable communication from the website to the extension, update the background script (background.js) of the extension as follows:

chrome.runtime.onMessageExternal.addListener(
    function(request, sender, sendResponse) {
        if (request) {
            if (request.message) {
                if (request.message == "version") {
                    sendResponse({version: 1.0});
                }
            }
        }
        return true;
    });

Website Script:

From the website, the following script can be used to check for the extension:

var hasExtension = false;

chrome.runtime.sendMessage(extensionId, { message: "version" },
    function (reply) {
        if (reply) {
            if (reply.version) {
                if (reply.version >= requiredVersion) {
                    hasExtension = true;
                }
            }
        }
        else {
          hasExtension = false;
        }
    });

The hasExtension variable can then be checked to determine the presence of the extension.

Manifest Update:

To allow messaging from the website to the extension, ensure that the extension's manifest.json file includes the following:

"externally_connectable": {
    "matches": ["*://localhost/*", "*://your.domain.com/*"]
},

2021 Update:

Note that since 2021, chrome.runtime.sendMessage throws an exception if the extension is not installed or disabled. To address this, validate the chrome.runtime.lastError property within the callback:

if (chrome.runtime.lastError) {
    // handle error 
}