Promise resolve not called because popup closes too fast

Question

I have the following piece of code:

  browser.windows.create({ url: urls }).then((newWindow) => {
    newWindow.tabs.slice(0, pins.length).map((tab, index) => {
      browser.tabs.update(tab.id, { pinned: true })
    })
  })

It works great when I prevent the popup from closing (via webdev tools) but in a regular use case, the resolve is not triggered.

Just saying: the video is not available anymore – Pierre-Adrien Jun 22 '18 at 16:40 — Pierre-Adrien, Jun 22 '18 at 16:40
@Pierre-AdrienBuisson Thanks, I removed the link. – Adrien Jun 25 '18 at 15:05 — Adrien, Jun 25 '18 at 15:05

score 2 · Accepted Answer · answered Jun 22 '18 at 16:37

I struggled with this same problem when I started working on my addon (In My Pocket for Firefox, you can have a look at the code on bitbucket if it can help, I implement exactly what I'm about to explain). I needed to trigger network calls to an API from the popup and do something when the request was succesful, and I got the exact same problem.

What you have to keep in mind is that code from a popup is executed as long as the popup is open. Closing the popup is like closing a webpage that contains Javascript: all its JS code is "unloaded", code execution stops, there's nothing more to handle the resolved promise.

A way to circumvent this is to implement the actual behaviour in a background script that will always be running all the time, and communicate between the background script and the popup via messages, through the runtime.sendMessage method and an event listener setup with runtime.onMessage.addListener.

Background scripts are the place to put code that needs to maintain long-term state, or perform long-term operations, independently of the lifetime of any particular web pages or browser windows.

You can get fancy with messages (sharing objects and not plain string) but you get the idea. And this way, your code that does not resolve immediately will still get processed all the way until it's finished, even if the popup is closed before the processing is over.

Promise resolve not called because popup closes too fast

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