upgrading chrome extension from manifest version2 to v3, need to get clipboard text in background.js

Question

Hi I am converting Google chrome extension from manifest version-2 to version-3

facing 2 issues those are mentioned below, but before that I will explain what extension in expected to do.

On click specific button on webpage I am calling console application that is copying JSON string in clipboard, then in chrome extension background.js I am getting clipboard data and passing it to content.js which is showing it in web page.

Errors / challenges:
1- Need to get clipboard text into a variable in background.js. I am able to get it in content.js but I need it to get it in background.js

2- I am getting these 2 error in background.js console, but extension is working

 Unchecked runtime.lastError: Native host has exited. Unchecked runtime.lastError: The message port closed before a response was received.

My Background.js looks like this

 var port = null; var tabId = null; chrome.runtime.onMessage.addListener((request, sender, sendResponse) => { tabId=sender.tab.id; var hostName = "my.console.app"; port = chrome.runtime.connectNative(hostName); port.onDisconnect.addListener(onDisconnected); sendResponse({status: 'ok'}); return true; }); function onDisconnected() { port = null; SendResponse(); } //this funciton need to upgrade to manifest version 3 because in v3 `chrome.extension.getBackgroundPage` is not compatible function SendResponse() { bg = chrome.extension.getBackgroundPage(); bg.document.body.innerHTML = ""; // clear the background page var helper = null; if (helper == null) { helper = bg.document.createElement("textarea"); helper.style.position = "absolute"; helper.style.border = "none"; document.body.appendChild(helper); } //Focus the textarea helper.select(); // perform a Paste in the selected control, here the textarea bg.document.execCommand("Paste"); // Send data back to content_script chrome.tabs.sendMessage(tabId, { action: "MY_CUSTOM_EVENT", response: helper.value }); }

content.js

 document.addEventListener("MY_CUSTOM_EVENT", function (data) { chrome.runtime.sendMessage({ runConsoleApp: true }, response => { }); }); async function copyToTheClipboard(textToCopy){ navigator.clipboard.readText().then(text => { //console.log('Pasted content: ', text); $('.simulateEidResponse').html(text).trigger('click'); }).catch(err => { console.error('Failed to read clipboard contents: ', err); }); }

Answer 1

Currently there's no way to do it in the background script due to crbug.com/1404835 .
In the future the workaround will be execCommand + offscreen API .

The only reliable solution that works regardless of whether the tab is focused or not is to use document.execCommand("Paste") in the content script.

// background.js

chrome.runtime.onMessage.addListener((msg, sender, sendResponse) => {
  if (msg.runConsoleApp) {
    chrome.runtime.connectNative('my.console.app')
      .onDisconnect.addListener(() => sendResponse(true));
    return true;
  }
});

// content.js

document.addEventListener('MY_CUSTOM_EVENT', async e => {
  await chrome.runtime.sendMessage({ runConsoleApp: true });
  document.querySelector('.simulateEidResponse').focus();
  document.execCommand('selectAll');
  document.execCommand('paste');
});