chrome extension dynamically change icon (without clicking)

Question

how can I make my chrome extension change icon (without clicking on it). I've got script that's checking if page has certain string and if it has I want my extension icon change from grey to colored one.

Answer 1

Updated Answer: For Manifest V3

Use chrome.action.setIcon({ path: "/example/path/image.png" }).

Source

Original Answer: For Manifest V2 and Under

The content script will need to send a message when it wants to set the icon e.g.

chrome.runtime.sendMessage({
    action: 'updateIcon',
    value: false
});

Then in the background script:

chrome.runtime.onMessage.addListener(function (msg, sender, sendResponse) {
    if (msg.action === "updateIcon") {
        if (msg.value) {
            chrome.browserAction.setIcon({path: "/assets/tick.png"});
        } else {
            chrome.browserAction.setIcon({path: "/assets/cross.png"});
        }
    }
});

Answer 2

In background you can do stuff like :

const updateIcon = tabId => {
  const icon = isDisabled() ? icons.disabled : icons.enabled;
  chrome.pageAction.setIcon({ tabId, path: icon });
};
chrome.tabs.onUpdated.addListener(updateIcon);

ref : https://github.com/gbleu/opteamissed/blob/master/background.js#L38