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Ⅰ. Introduction

I have read a lot and tried various ways of using the chrome.downloads API. But until now, I am still helpless in finding a way to use the chrome.downloads API.

Instructions from the docs didn't seem to help me much. So I decided to come here to ask and present to everyone about the problem that I am facing. I hope it helps many people.

My project uses manifest version 3.

Here is the GitHub link of the project: https://github.com/ATU8020/Use-API-chrome.downloads.git

Ⅱ. Presenting the Problem

Some related concepts are used:

  1. Service worker
  2. Content script
  3. Asynchronous function
  4. Synchronous function

Problems

I know that service workers require asynchronous function.

Listeners must be registered synchronously from the start of the page. LINK

Do not register listeners asynchronously, as they will not be properly triggered. LINK

But the chrome.downloads.download API returns a Promise:

API Chrome.downloads

See chrome.downloads docs.

That confused me. I have also tried other ways, such as with the content script. But after reading the docs, I know that the API chrome.downloads cannot be used directly. enter image description here

See content script docs.

Comment

That is the crux of my question. Any constructive comments and useful information are always appreciated.

Ⅲ. More Information

If using the API chrome.downloads in file popup.js it works; what does that mean?

I know that could be an alternative solution.

But what if you want to do something like download when you click on a contextMenu? Is it possible?

enter image description here

Mohamed Basiony
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ATU stackOverflow
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  • Use `onMessage`/`sendMessage` to communicate between different contexts. For example, if you present a button in a context that doesn't support `.downloads`, using messaging to communicate with a context that does support `.downloads` and then use that context to actually do the download. – Ouroborus Dec 21 '21 at 20:46
  • @Ouroborus The problem is what is the context in which you say API `chrome.downloads` can be used? – ATU stackOverflow Dec 21 '21 at 20:48
  • Any of the contexts that are under control of the extension. This would usually be background, popup, and content-script. (This does not include scripts that have been injected into the page by, for example, creating and inserting a script element directly in the page.) Note that a lot of the functions meant for use with extensions return promises. You'll need to get familiar with asynchronous programming to work with them. – Ouroborus Dec 21 '21 at 20:59
  • @Ouroborus "content-script" when inserted as API `chrome.scripting` also didn't work in my case, I tried. – ATU stackOverflow Dec 21 '21 at 21:14
  • Yeah, that's injection, not a content-script. A content-script is declared in the manifest and automatically handled. – Ouroborus Dec 21 '21 at 22:35

1 Answers1

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The fact that the method returns a Promise is not related to the way the listeners are registered.
You can call asynchronous code inside the listener in the background script.

  • ignoring the result:

    chrome.contextMenus.onClicked.addListener(info => {
  chrome.downloads.download({url: info.linkUrl});
});

  • using the result:

    chrome.contextMenus.onClicked.addListener(async info => {
  const downloadId = await chrome.downloads.download({url: info.linkUrl});
  console.log('downloadId:', downloadId);
});

    Beware: chrome.runtime.onMessage listener doesn't work with async functions yet, more info.

wOxxOm
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