main.js

chrome.tabs.query({ active: true, currentWindow: true }, function(tabs) {
  tabs.forEach(function(tab) {
    var button = document.createElement("button");
    button.textContent = "Add to pending list";
    button.className = "copy_code_button";
    button.addEventListener("click", function() {
      chrome.storage.local.get("pendingTabs", function(result) {
        const pendingTabs = result.pendingTabs || [];
        if (!pendingTabs.some(pendingTab => pendingTab.url === tab.url)) {
          pendingTabs.push({ title: tab.title, url: tab.url });
          chrome.storage.local.set({ pendingTabs: pendingTabs });
        }
      });
    });
    chrome.tabs.sendMessage(tab.id, { action: "addButton", button: button });
  });
});

chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
  if (request.action === "getPendingTabs") {
    chrome.storage.local.get("pendingTabs", function(result) {
      sendResponse(result.pendingTabs);
    });
    return true; 
  }
});