Implementing timeouts for node.js callbacks

Question

This is a typical situation in node.js:

asyncFunction(arguments, callback);

When asynFunction completes, callback

Answer 1

I ran into the same problem with a content script trying to open the port on the BG extension before the BG extension was ready. A work around was to wait for the BG extension to reply to a message and repeat this till successful. Here are the code snippets.

Content Script:

var nTimes     = 10;
var bIsReady = false;
checkBGReady();
function checkBGReady() {
  if (!bIsReady) {
    chrome.runtime.sendMessage({msgText: "hello "+nTimes}, function(response) {
      if (response && response.ack) {
        console.log("have response:"+response.ack+" "+nTimes);
        bIsReady = true;
        // continue with initialization
        bootStrap(sURL);
        checkReady();
      } else {
        console.log("have no ack response %o",response);
      }
    });
  }
  nTimes -= 1;
  if (nTimes > 0 && !bIsReady) {
    setTimeout(checkBGReady,100);
  }
}

BG Extension

  chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
    console.log(sender.tab ?"from a content script:" + sender.tab.url :"from the extension");
    if (request.msgText) {
      console.log("Have msg "+request.msgText);
       sendResponse({ack: "have contact "+request.msgText});
    }
  });

In my case it usually took after the first 100ms delay.