What's Changed

This release prepares jQuery 3.x apps better for a future migration to jQuery 4.x. It also drops support for jQuery 4.x - once you do update to jQuery 4.x, you should load jQuery Migrate 4.x.

Core

• Fill in & warn against $.fn.{push,sort,splice} by @mgol in #529
• Fill in & warn against jQuery.proxy by @mgol in #530
• Fix the selector module, make CI green by @mgol in #552
• Remove support for jQuery 4.x by @mgol in #554
• Patch push, sort & splice in jQuery >=3.7.0 by @mgol in #568
• Warn against jQuery.now & jQuery.camelCase by @mgol in #600

Ajax

• Fill in & warn against automatic JSON-to-JSONP promotion by @mgol in #531

Attributes

• Warn & restore boolean attribute & false setter treatment from 3.x by @mgol in #540

Data

• Patch camelCase behavior of $.fn.data, warn about Object.prototype by @mgol in #559
• Patch $._data & $._removeData as well, add more tests by @mgol in #570

Deferred

• Fill in & warn jQuery.Deferred.getStackHook by @mgol in #528
• Don't warn on setting getStackHook to the getErrorHook value by @mgol in #578

Event

• Patch jQuery.event.special's prototype by @mgol in #572

Selector

• Patch & warn against legacy selector pseudos by @mgol in #546

Others

• Docs: Add an entry for legacy-self-closed-tags in warnings.md by @mgol in #526
• Docs: Tweak README.md & warnings.md - update removal info by @mgol in #596
• Docs: Indicate which deprecated APIs are removed in 4.0; tweak a comment by @mgol in #606
• Tests: Migrate test runner to jquery-test-runner by @timmywil in #560
• Build: Test more browsers and jquery versions in pull requests by @mgol in #551

Full Changelog: 3.5.2...3.6.0

The only change compared to 4.0.0-beta.1 is fixing peerDependencies so that jQuery Migrate 4.0.0-beta.2 can be installed alongside jQuery 4.0.0-beta.2 or newer. 4.0.0-beta.1 required a stable jQuery 4.0.0 or newer which doesn't exist yet.

Read the 4.0.0-beta.1 release notes for more details.

The first jQuery Migrate pre-release compatible with jQuery 4.0.0-rc.1.

Major changes:

• Core: Remove support for jQuery 3.x (gh-472, gh-555)

• Core: Remove patches for breaking changes in jQuery 3.0.0 or older (gh-472, gh-555)

  The self-closed-tags patch remains, despite being a breaking change in jQuery
  3.5.0, not 4.0.0. There are a few reasons for that:

  1. It's an exception that a breaking change arrived in a non-major version bump.
     Some people may be upgrading from jQuery 3.4.0 or older and it's good to
     make it work for them.
  2. The patch is disabled by default, so the concern of people on newer jQuery
     3.x upgrading to jQuery 4.x with Migrate 4.x getting patches restoring
     behavior from an version older than the pre-upgrade one does not exist.
  3. This was a pretty big break, it may help people update if we still support
     it.

• Core: Don't reimplement deprecated but not removed APIs (gh-472, gh-555)

  This will save space and avoid potential divergence from Core.

  Also, simplify the deferred.pipe patch.

• Core: Use console.info for deprecations without removals (gh-472, gh-555)

  Also:

  1. Group warnings.md by this type.
  2. Rename jQuery.migrateWarnings to jQuery.migrateMessages.
  3. Rename jQuery.migrateDeduplicateWarnings to
     jQuery.migrateDeduplicateMessages.
  4. Adding "info" versions of some internal APIs.

• Core: Provide a package.json exports setup inspired by jQuery Core (gh-524, gh-566)

  The Migrate setup is simpler than Core as it doesn't have the slim or factory
  versions, but the core ideas are similar.

• Core: Don't warn just on access of jQuery.fn.push, etc., but when it's called (gh-571)

• Data: Patch & warn about props from Object.prototype in data objects (gh-561, gh-559)

• Data: Patch $._data as well (gh-569, gh-570)

• Event: Patch jQuery.event.global (gh-574)

• Event: Patch jQuery.event.special's prototype (gh-573, gh-542)

  Allow to use common Object.prototype properties on jQuery.event.special but
  warn as well.

This release introduces only one change:

• Make Migrate properly recognized as a CommonJS module in Node.js (#523, #525)

Note: you may also find jQuery Migrate 3.5.1 on npm. Do not use it, it's a result of a bad release.

Changes:

• Manipulation: Deprecate jQuery.UNSAFE_restoreLegacyHtmlPrefilter (#518)
• Attributes: Fix compatibility with jQuery 4.x (#496, #495)
• Docs: Mark jQuery.fn.load( [ eventData ], handler ) as removed (#482)
• Replace karma and testswarm with jQuery test runner (#503 + followups)