Question

I am using the following code to send a sample message from the content script:

function sendjsontrue()
{

        var arrCars = new Array("Toyota", "Mercedes", "BMW");           
            jsonStr = JSON.stringify(arrCars);
        chrome.extension.sendRequest({greeting: jsonStr},     function(response){
            console.log(response.farewell);
            });
        console.log("Message with header=greeting has been sent...");
}

The code in my popup.html to handle the message sent by content script, is given below–

<script>
chrome.extension.onRequest.addListener(
  function(request, sender, sendResponse) {
    console.log(sender.tab ?
            "from a content script:" + sender.tab.url :
            "from the extension");
  if (request.greeting == "hello")
      sendResponse({farewell: "goodbye"});
  else
      sendResponse({notfarewell:"Not goodbye"}); .
  });

</script>

The error that I am getting is given below–

Port error: Could not establish connection. Receiving end does not exist.
chrome/EventBindings:184Error in event handler for 'undefined': TypeError: Cannot read     property 'farewell' of undefined
at chrome-extension://nkmkgjckmjekpbghhildcfdlnbjeglkd/obtainformdata.js:81:25
at chrome/RendererExtensionBindings:238:13
at [object Object].dispatch (chrome/EventBindings:182:28)
at Object.<anonymous> (chrome/RendererExtensionBindings:134:27)

What have I done wrong here?

Answer 1

You should write the receiver code in a background page, instead of at the popup. Content scripts communicate with the background page, by default.

If you’re in need of decent documentation, have a look at:

• Chrome extension methods
• Background pages