[Bug]: CSP build triggers Chrome "Shared Storage API deprecated" warning #4788

PierreBultez · 2026-03-29T17:28:56Z

PierreBultez
Mar 29, 2026

Problem

The CSP parser enumerates all globalThis properties to build a set of known
globals. Accessing window.sharedStorage triggers Chrome's deprecation warning:

[Deprecation] Shared Storage API is deprecated and will be removed in a future release.

This causes Lighthouse "Best Practices" score to drop from 100 to 81.

This is the same class of issue that was already fixed for styleMedia.

Solution

Add "sharedStorage" to the skip list in the globalThis enumeration loop,
alongside the already-skipped "styleMedia".

Testing

Before: Chrome DevTools shows deprecation warning on any page using Alpine CSP
After: No deprecation warning, Lighthouse Best Practices score returns to 100
No functional impact: sharedStorage is not used by Alpine or typical web apps

How to reproduce

Pre-requisite

Chrome/Chromium >= 126
Node.js et npm

Steps

Create a minimal project with Alpine CSP :

git clone https://github.com/alpinejs/alpine.git alpinejs-bug
cd alpinejs-bug
npm install

Create a HTML file :

<!DOCTYPE html>
<html>
<head>
    <script src="./packages/alpinejs/dist/cdn.js" defer></script>
    <script src="./packages/csp/dist/cdn.js" defer></script>
    <title>Alpine CSP sharedStorage Bug</title>
</head>
<body>
<div x-data="{ count: 0 }">
    <button x-on:click="count = count + 1">
        Clicks: <span x-text="count">0</span>
    </button>
</div>
<script type="module">
    window.Alpine = Alpine;
</script>
</body>
</html>

Build and serve with a local server:

npm run build
npx serve .

Open Chrome and check :
- Open DevTools (F12) > Console
- Heed the warning : [Deprecation] Shared Storage API is deprecated and will be removed in a future release.
- Open the "Issues" tab in DevTools to see the details
Launch Lighthouse audit :
- DevTools > Lighthouse > "Best Practices"
- The score will be greatly impacted because of this warning.

Expected result

No deprecation warning should appear, because Alpine does not use the Shared Storage API — it only enumerates globals.

Observed result

Chrome detects access to window.sharedStorage and issues a deprecation warning, lowering the Lighthouse score.

Fix proposed in #4787

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[Bug]: CSP build triggers Chrome "Shared Storage API deprecated" warning #4788

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PierreBultez Mar 29, 2026

Problem

Solution

Testing

How to reproduce

Pre-requisite

Steps

Expected result

Observed result

Replies: 0 comments

PierreBultez
Mar 29, 2026