Question

I’ve been searching all over SO and reading through google docs but I can’t seem to find a solution.

My Chrome extension is injecting a content script and I want to set an onRequest.listener in order to sendRequests to the content script. This is the script I used to for the onRequest.listener. The problem is I keep getting this error for some unknown reason.

Error Message:

Uncaught TypeError: Cannot ready property 'onRequest' of undefined

contentscript.js line 1;

Here’s the relevant code…

Manifest.json

{
  "name": "Injector Extension",
  "version": "1.0",
  "manifest_version": 1,
  "icons": { "128": "icon.png" },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Injector Extension",
    "default_popup": "popup.html"
  },
  "options_page": "options.html",
  "background": {
    "page": "background.html"
  },
  "permissions": [
    "tabs", 
    "http://*/*",
    "https://*/*",
    "unlimitedStorage"],
  "content_scripts": [{
        "matches": [" (injector specific url) "],
        "js": ["contentscript.js"]
  }],
  "web_accessible_resources": ["js/script.js"] 
}

content script

 chrome.extension.onRequest.addListener(function(request, sender, sendResponse) {
  if (request.method == "fromPopup") {

    // Send JSON data back to Popup.
    sendResponse({data: "from Content Script to Popup"});

  } else {
     sendResponse({}); // snub them.
  }
});

popup

chrome.tabs.getSelected(null, function(tab) {
   chrome.tabs.sendRequest(tab.id, {method: "fromPopup", tabid: tab.id}, function(response) {
      console.log(response.data);
   });
});

Answer 1

chrome.extension.onRequest.addListener works only in extension context. It won’t run inside a content script.

chrome.extension.sendRequest works in content script context

Update accordingly and will work.

Edit: Exemplifying simple message passing:

Extension script:

chrome.extension.onRequest.addListener(function(r,s,sr){ 
     if(r==='HELLO') return sr.call(this,'BACK AT YOU');
});

Content script:

chrome.extension.sendRequest('HELLO', function(data){ alert(data); });
// will alert "BACK AT YOU"