jQuery Migrate helps upgrade between major versions. Include it after jQuery to get console warnings for deprecated API usage. Fix each warning by replacing old methods with modern equivalents, then remove Migrate.
Upgrading jQuery Versions
Use jQuery Migrate to find deprecated features:
<script src="jquery-3.7.1.js"></script>
<script src="jquery-migrate-3.4.1.js"></script>
// Check the browser console for warnings about deprecated APIs
// Then fix them before removing migrate