Hw to get background script executed when using a default po-up

Add-ons Development
#1

HI all,
I use a browser_action with a default pop-up. In addition I’d like to ‘fire-up’ a background script right in the beginning (registering a browser.runtime.onMessage.addListener(handleMessage)).

The idea is that the po-up ask for a password or starts a password request if non is set yet. Then, the password is send to the background script which manages the main activities of the extension.

The pop-up opens fine; however, I can not get the background script to be executed.
I have an entry in the manifest as follows:
“background”: {
“scripts”: ["/mainPage/mainPage.js"]
},

This alone does not seem to automatically execute the script. (I have put an alert in there to recognize execution).

-> what else (in addition to the manifest entry) do I need to do in order to get the background script get executed automatically such that it can register an onMessage event the pop-up can send to?

I could not find a comparable example in the examples list (please point me there if you know of one).
Thanks!
Alex

#2

The background script should get executed automatically when extension is loaded. There is no other way to “execute” it manually.

What does look strange is your file path: "/mainPage/mainPage.js", I’m pretty sure it should be "mainPage/mainPage.js"(without the / at the beginning).

#3

I tried both - with and without /.
Just putting an alert(“inside background script”); did not show up - so is my interpretation that it dies not run wrong because po-ups are suppressed?
how else can i test if it actually runs? or should the alert show up?

#4

It probably failed due to some error. Check the debugger console, plus check the browser console (Ctrl + Shift + J). Also, if you can, try to run it in Chrome, sometimes it prints errors that won’t show in Firefox.

#5

also registering a browserAction from inside the sript doesnot work; in fact:

alert(“inside”);
function backGroundTest() {
alert(“background script running”);
}
browser.browserAction.onClicked.addListener(backGroundTest);

does result in nothing showing up when the extension action is clicked

#6

I’m pretty sure you can’t use alert from background script - since you don’t have a visible DOM which could show it :slight_smile:.
Use normal console.log to print to console and then check the console.

The background script console can be accessed from “about:debugging#/runtime/this-firefox” page after clicking the “Inspect” button next to your addon name.

EDIT:
Maybe you need to rethink your architecture. I would suggest you to read some relevant docs:


Since you probably want to have some controls in your popup “page” that will communicate with background script using messages.

#7

using console.log as follows:
function backgroundTest() {
console.log(“executing background script function after click”);
}
console.log(“executing background script new”);
browser.browserAction.onClicked.addListener(backgroundTest);

I can see the “executing background script new” once when the ad-on is loaded.
This means background script is present as long as the browser is open.
However, clicking the button, the pou-up code is executed, but the second message from the background script does not appar; probably due to the fact that only one action can get registered to the browserAction and the po-up being first?

I next would try to register an onMessage and sending a message from the pop-up script.

Oh, I read those and many more mdn pages already several times. Just did not get it so far…

#8

You should be able to register as many event listeners as you want.
From MDN I can see that it won’t fire if you have a pop-up page defined in your manifest.

#9

Ok, finally got it -> can now send a message to the backgroudn script.
So only the alert() trapped me.
Thank you so much for your great help!

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