Howto send a message from content-script to inactive popup, chrome extension

Question

I want to log text on any webpage (using content-script to handle selection) into a database that is popup\'s resource in order to collect text in one place.

what i

Answer 1

A content script cannot send a message to an invisible popup, because the popup's context is inactive (closed) when it's hidden.

There are several solutions to your problem.

Option 1: No message passing, use storage events

If your "database" is in fact a simple key-value store, switch to the chrome.storage API. This API is available to the Content script and the popup, and comes with an event to notify you of value changes.

Example:

// Get notified of changes (in the popup?)
chrome.storage.onChanged.addListener(function(changes, areaName) {
    // Do whatever you want with the changes.
});
// Initialization of the popup (print initial information?)
chrome.storage.local.get({keyName: 'defaultValue'}, function(items) {
    // Do something with items.keyName
});

// Content script, storage (remember document title?)
chrome.storage.local.set({keyName: document.title});

Option 2: Pass messages to the background/event page

The popup and the background / event page share the same process. Any database tied to the popup is also available to the background page, and vice versa. A high-level overview of this method:

1. Content script sends a message to the background page.
2. The background page stores the value in the database
3. If the popup is open, update the popup's view.
4. If the popup is opened ^{(so it was closed before)}, it should read the database (either directly, or by reading data from the background page using chrome.runtime.getBackgroundPage) and handle the results.

I've provided the code corresponding to this flow in this answer.