Modern Web Guidance
JetBrainsOfficialCreated by Google ChromeDistributed by JetBrains
- Skill
- Tool integration
- Software development
- Apache-2.0
- Low risk
AutoGineer summary
Written by AutoGineer from the skill’s own files, not by the author
This skill provides a structured way to access up-to-date web development patterns, ensuring that implementations follow modern standards rather than relying on potentially outdated training data. It covers a wide range of frontend topics including UI components, performance optimization, browser APIs, and form handling. By integrating this tool, developers can search for specific use cases and retrieve detailed, framework-agnostic guides that include browser support and fallback recommendations.
What it does
- Searches for standardized web development patterns and best practices.
- Retrieves detailed implementation guides for specific frontend use cases.
- Provides guidance on browser compatibility and necessary fallbacks.
- Helps avoid ad-hoc solutions and unnecessary dependency bloat.
- Supports modern web features like container queries, view transitions, and performance APIs.
When to use it
- At the beginning of any frontend feature implementation.
- Before creating new components to check for existing standardized patterns.
- When evaluating the browser support requirements for modern web features.
- When needing to implement performance optimizations like LCP or content-visibility.
Advantages
- Ensures use of current, recommended web development practices.
- Reduces technical debt by discouraging ad-hoc implementations.
- Provides clear guidance on handling browser compatibility and fallbacks.
- Promotes the use of native browser capabilities over heavy external dependencies.
Usage examples
- “I need to implement a modal using modern web standards. What is the best approach?”
- The agent searches for modal-related guides and retrieves the recommended implementation pattern, including any necessary browser fallbacks.
- “How can I optimize the loading priority of my LCP images?”
- The agent searches for image optimization guides and retrieves the specific instructions for using fetch priority to improve performance.
Install
Download the skill as a ZIP:
https://autogineer.com/agent-skills/jetbrains/modern-web-guidance/downloadUnzip it into the cross-client skills folder of your project:
mkdir -p .agents/skills && unzip modern-web-guidance.zip -d .agents/skills
Documentation by Google Chrome
Modern Web Guidance
A skill to search for specific web development use cases and retrieve their corresponding best practice guides.
When to use
Must use this skill:
At the start of implementing any web feature.
Before creating a new component, to check if a standardized pattern already exists.
To avoid implementing ad-hoc solutions or loading large dependencies unnecessarily.
Usage Instructions
Step 1. Search Use Cases
Search with an action-oriented query summarizing what you want to achieve using the search command. Run modern-web-guidance directly with npx.
npx -y modern-web-guidance@latest search "<query>" --skill-version 2026_05_16-c5e7870Example Output:
[
{
"id": "optimize-image-priority",
"description": "Optimize the loading priority of Largest Contentful Paint (LCP) candidate images.",
"category": "performance",
"featuresUsed": [ "Fetch priority" ],
"tokenCount": 985,
"similarity": 0.7289
},
{
"id": "defer-rendering-heavy-content",
"description": "Reduce rendering times in content-heavy web pages by deferring rendering for offscreen content.",
"category": "performance",
"featuresUsed": [ "content-visibility", "hidden=\"until-found\"" ],
"tokenCount": 1250,
"similarity": 0.6961
}
]Note: If search results are vague, return no matches, or show low similarity scores, run the
listcommand to browse all guides:npx -y modern-web-guidance@latest list
Step 2. Retrieve Best Practices
Once you have a relevant id from the search results, call this script using the retrieve command to get the full guide. You can pass multiple IDs separated by commas.
npx -y modern-web-guidance@latest retrieve "<id>"Example Output:
The markdown content of the guide describing implementation steps...
Using npx
IMPORTANT: on Windows, using
npxmay fail. Usenpx.cmd ...instead.Network access is required for fetching npm packages needed by the task.
If the
npx -y modern-web-guidance…command hangs, you may be offline. Try running again in offline mode:npx --offline ….The
--skill-versionflag is used to determine if this SKILL.md is out of date. If it is, a warning message is logged to stderr.
Guidelines
Always search first to find the most relevant guides.
These guides are usually framework-agnostic; adapt them correctly to your setup.
Do not hallucinate guides or ignore them; they represent the preferred local standard for the user's project.
Interpreting Browser Support & Fallbacks
Default Behavior: All guides assume Baseline Widely available features are safe to use without fallbacks. For features that are not Baseline widely available, you MUST follow the fallback recommendations in the guide, unless the user has specified a custom browser support policy.
Custom Policies: If the user has already defined explicit browser support requirements, use the browser compatibility data in the guide to determine if a fallback can be safely ignored.
For Baseline YYYY targets, a feature satisfies this target if its "Baseline since" date is <= YYYY.
Policy Examples:
"Do not implement feature fallbacks." (for exploratory prototypes of the cutting-edge web)
"Safari 17.4+" (for internal tools targeting macOS or Tauri-based desktop apps)
"Never recommend or implement polyfills; if a Baseline Newly Available feature is required for core functionality, provide a lightweight custom fallback or redesign the approach." (to minimize bundle size and avoid technical debt)
"Assume a modern execution environment where Baseline Newly Available features can be used natively, provided they are strictly feature-detected and degrade gracefully." (for progressive enhancement strategies)
Reactive Policy Discovery: Watch for environmental cues to suggest documenting a policy in CLAUDE.md or AGENTS.md. Suggest this if the developer:
Mentions building for a restricted runtime (e.g., Electron or Tauri).
Explicitly excludes specific targets (e.g., "we don't support Desktop Chrome").
Expresses hesitation about polyfill complexity, bundle size, or performance cost.
Questions if a feature is safe to use without fallbacks.
No defined policy format. This is an example:
**Browser Support:** Allow Newly Available features, but only adopt custom fallback code that adds <= 20 lines and does not require external dependencies.
Files
- ATTRIBUTION.mdAdded by AutoGineer939 B
- LICENSE11.1 KiB
- SKILL.md5.7 KiB
- guides/accessibility/accessibility.md24.0 KiB
- guides/accessibility/accessible-error-announcement.md6.9 KiB
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- guides/html/html.md17.5 KiB
- guides/passkeys/passkey-authentication.md9.7 KiB
- guides/passkeys/passkey-conditional-create.md6.5 KiB
- guides/passkeys/passkey-management.md9.3 KiB
- guides/passkeys/passkey-reauthentication.md4.9 KiB
- guides/passkeys/passkey-registration.md9.3 KiB
- guides/passkeys/passkeys.md4.2 KiB
- guides/performance/batch-analytics-events.md6.4 KiB
- guides/performance/break-up-long-tasks.md2.1 KiB
- guides/performance/calculate-total-foreground-time.md2.9 KiB
- guides/performance/conditional-async-dependencies.md3.6 KiB
- guides/performance/defer-rendering-heavy-content.md6.3 KiB
- guides/performance/defer-work-until-scroll-ends.md3.3 KiB
- guides/performance/deprioritize-background-fetches.md1.8 KiB
- guides/performance/detect-initial-visibility-state.md4.5 KiB
- guides/performance/efficient-background-processing.md5.0 KiB
- guides/performance/faster-spa-view-transitions.md3.4 KiB
- guides/performance/full-session-analytics.md5.7 KiB
- guides/performance/identify-heavy-scripts.md4.2 KiB
- guides/performance/identify-inp-causes.md5.4 KiB
- guides/performance/improve-next-page-load-performance.md7.1 KiB
- guides/performance/interactions-in-complex-layouts.md3.4 KiB
- guides/performance/optimize-image-priority.md4.0 KiB
- guides/performance/optimize-preload-priority.md3.3 KiB
- guides/performance/optimize-script-priority.md2.6 KiB
- guides/performance/performance.md17.9 KiB
- guides/performance/resolution-optimized-pseudo-elements.md2.3 KiB
- guides/performance/schedule-tasks-by-priority.md2.2 KiB
- guides/performance/sequence-distributed-events.md3.5 KiB
- guides/privacy/privacy.md11.0 KiB
- guides/security/security.md25.2 KiB
- guides/user-experience/adapt-scrollbar-to-contrast-preferences.md3.5 KiB
- guides/user-experience/anchor-positioning-tab-underline.md2.9 KiB
- guides/user-experience/animate-element-entry-exit.md5.0 KiB
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- guides/user-experience/apply-webgl-shaders.md9.9 KiB
- guides/user-experience/calculate-event-differentials.md4.4 KiB
- guides/user-experience/calculate-with-intrinsic-sizes.md9.6 KiB
- guides/user-experience/capture-location-agnostic-data.md3.6 KiB
- guides/user-experience/carousel-slide-effects.md8.1 KiB
- guides/user-experience/carousel-snap-highlights.md5.7 KiB
- guides/user-experience/child-state-based-styling.md4.8 KiB
- guides/user-experience/complex-shapes.md3.5 KiB
- guides/user-experience/component-specific-light-dark-theme.md9.3 KiB
- guides/user-experience/consistent-cross-document-transitions.md11.8 KiB
- guides/user-experience/content-based-styling.md5.2 KiB
- guides/user-experience/coordinate-global-events.md3.5 KiB
- guides/user-experience/cross-document-transitions.md4.4 KiB
- guides/user-experience/customize-scrollbar-color-and-thickness.md2.4 KiB
- guides/user-experience/dark-mode.md15.2 KiB
- guides/user-experience/declarative-button-actions.md5.4 KiB
- guides/user-experience/declarative-dialog-popover-control.md9.2 KiB
- guides/user-experience/deliver-optimized-decorative-images.md2.8 KiB
- guides/user-experience/design-token-reactivity.md5.7 KiB
- guides/user-experience/directional-navigation-transitions.md4.9 KiB
- guides/user-experience/dynamic-sibling-animations.md2.6 KiB
- guides/user-experience/dynamic-sibling-styling.md3.6 KiB
- guides/user-experience/export-html-media-from-canvas.md11.2 KiB
- guides/user-experience/expose-canvas-content-to-browser-features.md14.1 KiB
- guides/user-experience/flicker-free-client-side-ab-testing.md8.5 KiB
- guides/user-experience/fluid-scaling.md3.0 KiB
- guides/user-experience/format-human-readable-durations.md4.2 KiB
- guides/user-experience/group-element-transitions.md5.0 KiB
- guides/user-experience/improve-text-layout-and-legibility.md5.1 KiB
- guides/user-experience/individual-transform-properties.md3.6 KiB
- guides/user-experience/interactive-content-in-3d-scenes.md13.3 KiB
- guides/user-experience/interactive-content-reveal.md5.1 KiB
- guides/user-experience/interest-triggered-action-previews.md4.1 KiB
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- guides/user-experience/light-dismiss-a-dialog.md3.6 KiB
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- guides/user-experience/pull-to-reveal.md4.7 KiB
- guides/user-experience/reduce-style-repetition.md3.9 KiB
- guides/user-experience/resilient-context-menus-and-nested-dropdowns.md4.9 KiB
- guides/user-experience/same-document-transitions.md8.3 KiB
- guides/user-experience/scroll-entry-exit-effects.md7.8 KiB
- guides/user-experience/scroll-position-aware-elements.md3.6 KiB
- guides/user-experience/scroll-progress-indicator.md6.7 KiB
- guides/user-experience/scroll-snap-realtime-feedback.md6.7 KiB
- guides/user-experience/scroll-snap-state-sync.md3.9 KiB
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- guides/user-experience/shrinking-header-on-scroll.md6.3 KiB
- guides/user-experience/size-aware-styling.md2.9 KiB
- guides/user-experience/soft-edge-content-fade.md2.6 KiB
- guides/user-experience/stabilize-reactive-state.md3.5 KiB
- guides/user-experience/stack-drill-down.md32.9 KiB
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- guides/user-experience/support-global-calendar-systems.md5.7 KiB
- guides/user-experience/swipe-to-remove.md26.2 KiB
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- guides/webmcp/agentic-javascript-tools.md4.1 KiB
- guides/webmcp/webmcp.md3.7 KiB
guides/passkeys/passkey-management.md
Passkey Management Guide
This guide details how to enable users to view, rename, and delete their registered passkeys while keeping saved credentials perfectly synchronized between the server and the user's password managers using the Signal API.
Server-Side Operations
Your backend database layer and endpoints MUST support common CRUD actions for registered credentials. Decoupled from framework-specific libraries, the server exposes endpoints to:
List all user credentials: Fetch all
StoredPasskeyCredentialrecords matching the signed-in user's ID.Update credential names: Accept a new custom string name for a specific credential ID and persist the update.
Delete credentials: Remove a specific credential ID from the database.
// Node.js routing example for credential CRUD
router.get('/api/credentials', checkUserAuthenticated, async (req, res) => {
const list = await db.findCredentialsByUserId(req.user.id);
return res.json(list);
});
router.put('/api/credential/:id', checkUserAuthenticated, async (req, res) => {
const { id } = req.params;
const { name } = req.body;
const cred = await db.findCredentialById(id);
if (!cred || cred.passkeyUserId !== req.user.id) {
return res.status(404).json({ error: 'Credential not found.' });
}
cred.name = name;
await db.saveCredential(cred);
return res.json(cred);
});
router.delete('/api/credential/:id', checkUserAuthenticated, async (req, res) => {
const { id } = req.params;
const cred = await db.findCredentialById(id);
if (!cred || cred.passkeyUserId !== req.user.id) {
return res.status(404).json({ error: 'Credential not found.' });
}
await db.deleteCredential(id);
return res.json({ success: true });
});Client-Side Management UI
Render a dedicated settings panel allowing users to easily audit and manage their registered authentication options:
Display saved list: Fetch list from your endpoint and render individual credential rows. If the response is empty, render a helpful empty-state message (e.g., "No passkeys found").
Map AAGUID Metadata: For each passkey, lookup its
aaguidproperty against your local registry to render its provider details. See Determine the passkey provider from AAGUID section for more details.Per-Item UI Requirements: Every row inside the list container MUST render:
Provider Icon: AAGUID-derived image or data URI.
Provider/Custom Name: AAGUID-derived name or user-renamed string.
Registration Date: The database-persisted raw epoch timestamp
registeredAtformatted to a human-readable date for client display.Last Used Date: The database-persisted raw epoch timestamp
lastUsedAtformatted to a human-readable date (if present) for client display.Rename Button: Triggers a rename text input modal.
Delete Button: Triggers deletion.
Conditional "Create Passkey" Button:
Offer a prominent "Create passkey" registration trigger button on the management page. Before rendering this UI element, the page MUST feature-detect capabilities using
PublicKeyCredential.getClientCapabilities()to verify platform authenticator is supported. If passkeys are unsupported, hide this button and gracefully encourage standard MFA enrollments instead.Allow registering a security key by omitting
authenticatorSelection.authenticatorAttachmentonnavigator.credentials.create()call.
Signal API Synchronization
The Signal API lets the application communicate credential states to password managers, keeping the user's synced vaults and your backend database in lockstep.
Parameter Encoding Rule:
All
userIdand credential ID parameters passed to Signal API methods (signalAllAcceptedCredentials,signalCurrentUserDetails) MUST be Base64URL-encoded strings.
Initiating Page Load Sync:
The application MUST invoke
signalAllAcceptedCredentials()automatically in aDOMContentLoadedpage load event listener.
Management Updates Sync:
The application MUST invoke
signalAllAcceptedCredentials()immediately within your delete credential click handler post-fetch.The application MUST invoke
signalCurrentUserDetails()immediately within your username or display name rename click handler post-fetch.
// Client-side management synchronization ES module
import { listFetch, renameFetch, deleteFetch } from './api.js';
// Base64URL-encoded User ID string (illustration only)
const base64UrlUserId = "M2YPl-KGnA8";
async function syncAcceptedCredentials(currentCredentialsList) {
try {
const credentialIds = currentCredentialsList.map(c => c.id); // Map of Base64URL credential ID strings
await PublicKeyCredential.signalAllAcceptedCredentials({
rpId, // RP ID must match the one defined on the server
userId: base64UrlUserId, // User ID Base64URL-encoded string
allAcceptedCredentialIds: credentialIds
});
} catch (e) {
console.error('SignalAllAcceptedCredentials sync failure:', e);
}
}
async function loadManagementPanel() {
const response = await listFetch();
const list = await response.json();
renderUI(list);
// Sync on page load
await syncAcceptedCredentials(list);
}
async function performDelete(credentialId) {
const response = await deleteFetch(credentialId);
if (response.ok) {
const updatedResponse = await listFetch();
const updatedList = await updatedResponse.json();
renderUI(updatedList);
// Sync after deletion
await syncAcceptedCredentials(updatedList);
}
}
async function performRename(rpId, userId, updatedName, updatedDisplayName) {
const response = await renameFetch({ name: updatedName, displayName: updatedDisplayName });
if (response.ok) {
try {
await PublicKeyCredential.signalCurrentUserDetails({
rpId, // RP ID must match the one defined on the server
userId, // Base64URL-encoded user ID
name: updatedName, // Updated username
displayName: updatedDisplayName // Updated display name
});
} catch (e) {
console.error('SignalCurrentUserDetails sync failure:', e);
}
}
}Determine the passkey provider from AAGUID {: #aaguid }
An AAGUID (Authenticator Attestation Globally Unique Identifier) is a 128-bit identifier that represents the model of the authenticator, not a specific instance. It is included in the authenticator data during passkey registration and can be used to determine which passkey provider (e.g. Google Password Manager, iCloud Keychain, 1Password) created a credential.
AAGUID should only be used to help users with passkey management. It can be modified unless cryptographically attested, which platform passkeys currently don't support.
1. AAGUID Registry
A community-maintained JSON mapping of AAGUIDs to provider names and icons is available at:
https://raw.githubusercontent.com/passkeydeveloper/passkey-authenticator-aaguids/refs/heads/main/combined_aaguid.jsonEach entry has the following schema:
{
"<aaguid-uuid>": {
"name": "Provider Name",
"icon_light": "data:image/png;base64,...",
"icon_dark": "data:image/png;base64,..."
}
}2. Using AAGUID After Registration
After verifying a registration response, read the aaguid from the registration result and look it up against the registry to populate the credential's name and providerIcon:
Before looking up the AAGUID in the registry, check if it equals '00000000-0000-0000-0000-000000000000'. If so, skip the registry lookup and set name to a fallback (e.g. device name from user-agent, or "Unknown passkey provider") and providerIcon to undefined. Only look up the registry for non-zeroed AAGUIDs.
import aaguids from './aaguids.json' with { type: 'json' };
const { aaguid } = registrationInfo;
if (aaguid === '00000000-0000-0000-0000-000000000000') {
// use the device name as the passkey provider based on
// the information derived from the user agent string,
// or just say "Unknown passkey provider"
} else {
const provider = aaguids[aaguid];
const credential = {
// ...other fields
aaguid,
name: provider?.name || 'Unknown passkey provider',
providerIcon: provider?.icon_light,
};
}Fallback Strategies
Passkey feature detection fallback
Baseline status for the api.PublicKeyCredential.getClientCapabilities_static capability: Newly available. It's been Baseline since 2025-02-06. Supported by: Chrome 133 (Feb 2025), Edge 133 (Feb 2025), Firefox 135 (Feb 2025), and Safari 17.4 (Mar 2024).
Always install 'webauthn-polyfills' and import it in the context.
Consider as long as PublicKeyCredential is supported, PublicKeyCredential.getClientCapabilities is also supported.
import 'webauthn-polyfills';Signal API Synchronization Fallback
Web authentication signal methods has limited availability.
Supported by: Chrome 132 (Jan 2025), Edge 132 (Jan 2025), and Safari 26 (Sep 2025).
Unsupported in: Firefox.
If the browser does not support PublicKeyCredential.parseRequestOptionsFromJSON, use the 'webauthn-polyfills':
<script type="module">
if (!PublicKeyCredential.parseRequestOptionsFromJSON) {
await import('https://unpkg.com/webauthn-polyfills');
}
</script> This will also add support for PublicKeyCredential.prototype.toJSON.
Requirements and compatibility
Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta
“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.
Needs: Needs Node.js
Security
What our scanner noticed· Low risk
- Instructions that use the network
A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.
Attribution and licence
- Created by
- Google Chrome
- Publisher
- JetBrains (Official)
- Distributed by
- JetBrains
- Source
- JetBrains/skills · modern-web-guidance · commit 3f53782
- Licence
- Apache License 2.0 (redistribution allowed)
- ATTRIBUTION.md (written by AutoGineer)
- Synced
AutoGineer is not affiliated with or endorsed by Google Chrome or JetBrains.
Download ZIP
The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download modern-web-guidance.zip