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Pulsebest-practices

Avoid Deprecated APIs

What This Audit Checks

This audit detects calls to web platform APIs that browsers have officially deprecated. These include methods like document.write(), AppCache, legacy webkitURL, and other APIs scheduled for removal.

Why It Matters

Deprecated APIs can break at any time when browsers ship new versions. Relying on them creates ticking time bombs in your codebase that cause runtime errors for users with no warning.

How to Fix It

  • Check the console warnings Lighthouse reports and identify which deprecated APIs your page uses.
  • Replace document.write() with DOM manipulation methods like document.createElement() and appendChild().
  • Swap AppCache for Service Workers if you are still using the Application Cache manifest.
  • Update third-party libraries that call deprecated APIs. Often the fix is simply upgrading to the latest version.
// Bad: deprecated API
document.write('<script src="analytics.js"><\/script>');

// Good: modern alternative
const script = document.createElement('script');
script.src = 'analytics.js';
document.head.appendChild(script);

How Pulse Tracks This

Pulse flags this audit in your Lighthouse best-practices score. When the audit fails, Pulse shows which elements triggered it so you can fix them directly.

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