Web features: [Fetch priority](https://webstatus.dev/features/fetch-priority) [Fetch](https://webstatus.dev/features/fetch) > [!NOTE] > **Note:** These guides are authored for AI coding agents (apologies for the robotic tone!). To have your coding agent adopt these patterns automatically, check out [Modern Web Guidance](https://github.com/GoogleChrome/modern-web-guidance). When a page performs multiple simultaneous network requests, they often compete for the same bandwidth. Non-critical data such as analytics, logging, or background synchronization should be deprioritized so that user-initiated or critical data fetches can complete more quickly. ## How to implement 1. **Identify background requests** : Determine which `fetch()` calls are for non-essential data that doesn't impact the immediate user experience. 2. **Apply fetch priority** : Add the `priority: 'low'` option to the `fetch()` initialization object. ## Example code ```javascript // Use high priority (default) for critical UI updates const criticalData = await fetch('/api/data'); // Explicitly deprioritize background analytics fetch('/api/analytics', { method: 'POST', body: JSON.stringify(eventData), // Lower the priority to prevent network contention priority: 'low' }); ``` ## Best practices - **DO** use `priority: 'low'` for analytics, beacons, or telemetry data that isn't required for the current view. - **DO** use `priority: 'low'` for "prefetching" data that the user *might* need later, ensuring it doesn't slow down what they need *now*. - **DO NOT** use `priority: 'low'` for fetches that are critical to the user experience. - **DO NOT** use the deprecated `importance` key in the fetch options object. The correct key is `priority`. ## Fallback strategy The `priority` option in the Fetch API is a progressive enhancement. Browsers that do not support it will ignore the option and treat the request with default priority. No explicit feature detection or fallback logic is required for basic usage. Source: [deprioritize-background-fetches guide on GitHub](https://github.com/GoogleChrome/modern-web-guidance-src/blob/main/guides/performance/deprioritize-background-fetches/guide.md)