Chrome Extension - Passing object from page to context script

Question

I\'m writing a chrome extension and I\'m struggling to pass an object back from the main page to the context script. I can\'t seem to access the window\'s variables.

Answer 1

Above answer may work but I don't think it is the correct way ...

First:

If you already published your extension, get the application key and put it into your manifest "key" as described here:

• install Chrome Extension Source Viewer
• CRX -> view extension source -> enter published application URL -> enter
• open developer tools (F12) -> go to console

• copy the "key" atring from the console into your local manifest.json:
  

  "key": "MIIBIjANBgkqhkiG9w...RwIDAQAB",

This will ensure your local and published extension have the same extensionId

Second:

• load your local extension
• find out your extensionId by going to chrome://extensions and looking for ID under your extension title

Third:

in your background script (ie background.js) listen for msgs like this:

chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
   if (message.name === 'msg1') {
      alert(message.key1);
   }
});

in your content script (ie contentScript.js) send msgs like this:

chrome.runtime.sendMessage(extensionId, { name: 'msg1', key1: 'value1'}, undefined, (response) => {});

(replace extensionId with the one you got in the second step)