Question about getting a model and handling downloads

[Raymond Camden]

For many of my demos, I take the easy way out and if the status for the API is not "available", I just abort. That's wrong of course, but was simpler, and as I'm just building demos, I figured it was ok to cut some corners.

Now - I'm trying to be better about that - and wanted to update my default code to better handle these cases. I started working on a somewhat complex wrapper that I could reuse and I realized I had over-engineered it. I have a simpler solution, and would love a sanity check. 

This sample code is for Prompt, but obviously I'd use it for all. Ok, given you've already checked for the presence of window.LanguageModel and status was either available or downloadable, consider this code:

async function doAITest() {
console.log('doAITest');
session = await LanguageModel.create({
monitor(m) {
m.addEventListener('downloadprogress', e => {
console.log(`Downloading prompt model: ${e.loaded * 100}%`);
});
}
});
console.log('hello', session);
}

From what I see - on a virgin profile, I get the download messages, and when it's done, the final console runs. On reload after download, I get the final console. 

So outside of ensuring I give proper user feedback (more than a console message), this simple code is perfectly fine to handle both cases, right?

[François Beaufort]

Ideally, there would be a progress bar somewhere to indicate to the user what's happening while LanguageModel.create() is called.

Otherwise, LGTM ;)

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[Raymond Camden]

Thank you - this will also help simplify that comic demo you're helping on. 

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===========================================================================
Raymond Camden

Email : raymon...@gmail.com
Blog : www.raymondcamden.com
Twitter: raymondcamden

[Raymond Camden]

So, taking what I've learned today, I'm working on a blog post that shows "kinda" best practice for this (not saying it's perfect of course) and came up with the demo here:

https://codepen.io/cfjedimaster/pen/LEpqeMp?editors=1010

Which shows a wrapper function, getLM, that lets you pass an object of options and a 'notifier' function that gets passed the current loaded value of a download. From outside, you can do:

session = await getLM({}, loaded => {
console.log(`My own notifier, loaded value is ${loaded}`);
});

Which the idea that your notifier function will do something nice in the UI for the user. So far, this works fine, but I'm seeing that the downloadprogress event *always* fires. Once for 0, once for 1. Two questions/ideas:

1) Is this just a temporary bug I can ignore?

2) If not, should my wrapper perhaps do a call to availability, and if it's available, disregard any custom notification function passed it? (

[François Beaufort]

On Fri, Sep 5, 2025 at 7:17 PM Raymond Camden <raymon...@gmail.com> wrote:

So, taking what I've learned today, I'm working on a blog post that shows "kinda" best practice for this (not saying it's perfect of course) and came up with the demo here:

https://codepen.io/cfjedimaster/pen/LEpqeMp?editors=1010

Which shows a wrapper function, getLM, that lets you pass an object of options and a 'notifier' function that gets passed the current loaded value of a download. From outside, you can do:

session = await getLM({}, loaded => {
console.log(`My own notifier, loaded value is ${loaded}`);
});

Which the idea that your notifier function will do something nice in the UI for the user. So far, this works fine, but I'm seeing that the downloadprogress event *always* fires. Once for 0, once for 1. Two questions/ideas:

1) Is this just a temporary bug I can ignore?

As highlighted in https://github.com/webmachinelearning/prompt-api?tab=readme-ov-file#download-progress, at least two events, with e.loaded === 0 and e.loaded === 1, will always be fired. This is true even if creating the model doesn't require any downloading.

[Raymond Camden]

Cool - I'll go with the option of checking the status and disabling notifications if available. And... I swear I read *most* of the docs. Honest. ;)

[Thomas Steiner]

Hey Raymond and all,

FWIW, I'm working on a best practice article on exactly this topic and hope to have it out soon. Watch this space (well, the announcement list you are all on as well) for updates :-)

Cheers,

Tom

To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/chrome-ai-dev-preview-discuss/CAK2avF9GGB5TNOW0QPovCpkKxN57xaSD%3D1%3DeNvPaPnSrV055Mg%40mail.gmail.com.

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Thomas Steiner, PhD—Developer Relations Engineer (blog.tomayac.com, toot.cafe/@tomayac)

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