Can I get access to localStorage of site from chrome extension?

Question

My chrome extension has two state: 1. Some site has auth data in localStorage (another domain), so I have to show main window. 2. There is no auth data, so I have to show window with login and password form.

In order to define if auth data is presented, I would like to check his localStorage, but it looks like it's impossible.

However, chrome.storage.local.get and chrome.storage.local.setworks perfectly for localStorage of extension.

Or is there approach to do this - get access to localStorage of another site ?

Answer 1

Yes, you can execute a script on the page to access the local storage. There are a couple of different ways you can do this, including content scripts or injected scripts.

I'm using chrome-extension-async for async/await support.

For instance in popup.js

document.addEventListener('DOMContentLoaded', async () => {
    try {
        const key = "foobar"

        // Get the current tab
        const tabs = await chrome.tabs.query({ active: true, currentWindow: true });
        const tab = tabs[0]; 

        // Execute script in the current tab
        const fromPageLocalStore = await chrome.tabs.executeScript(tab.id, { code: `localStorage['${key}']` });

        // Store the result  
        await chrome.storage.local.set({[key]:fromPageLocalStore[0]});
    } 
    catch(err) {
        // Log exceptions
    }
});