# jQuery: what changed from 3 to 4

- Product: jQuery (https://whatsnew.fyi/product/jquery)
- Vendor: OpenJS Foundation
- Range: changelog entries numbered after 3.7.1 up to and including 4.0.0, stable releases only
- Entries below: 1 release (newest first)
- Resolved: 3 is 3.7.1 and 4 is 4.0.0, the newest stable release of each major we track
- Carrying security changes: 0 · CVEs mentioned: 0 · Mentioning breaking changes: 0 · Removing or deprecating something: 1
- Page: https://whatsnew.fyi/product/jquery/compare/3...4

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

## What changed (20 changes, grouped by kind)

### Added

#### 4.0.0 (2026-01-18)

- Support binary data including FormData in Ajax
- Support headers for script transport even when cross-domain
- Support null as success functions in jQuery.get

### Changed

#### 4.0.0 (2026-01-18)

- Don't treat array data as binary in Ajax requests
- Allow processData: true even for binary data
- Don't auto-execute scripts unless dataType provided
- Execute JSONP error script responses
- Simplify jQuery.ajaxSettings.xhr
- Make .attr(name, false) remove for all non-ARIA attrs
- Refactor val(): don't strip carriage return, isolate IE workarounds

### Fixed

#### 4.0.0 (2026-01-18)

- Make responseJSON work for erroneous same-domain JSONP requests
- Avoid CSP errors in the script transport for async requests
- Overwrite s.contentType with content-type header value if any
- Do not execute scripts for unsuccessful HTTP responses
- Don't stringify attributes in the setter
- Fix dimensions of table col elements
- Make offsetHeight(true) etc. include negative margins

### Removed

#### 4.0.0 (2026-01-18)

- Drop the json to jsonp auto-promotion logic
- Drop the toggleClass(boolean|undefined) signature

### Deprecated

#### 4.0.0 (2026-01-18)

- AJAX event aliases

## Release notes

### 4.0.0 — Release 4.0.0

- Date: 2026-01-18
- Version: 4.0.0
- Original notes: https://github.com/jquery/jquery/releases/tag/4.0.0
- Permalink: https://whatsnew.fyi/product/jquery/releases/4.0.0

- **changed** — Don't treat array data as binary in Ajax requests
- **changed** — Allow processData: true even for binary data
- **added** — Support binary data including FormData in Ajax
- **added** — Support headers for script transport even when cross-domain
- **added** — Support null as success functions in jQuery.get
- **changed** — Don't auto-execute scripts unless dataType provided
- **fixed** — Make responseJSON work for erroneous same-domain JSONP requests
- **changed** — Execute JSONP error script responses
- **fixed** — Avoid CSP errors in the script transport for async requests
- **removed** — Drop the json to jsonp auto-promotion logic
- **fixed** — Overwrite s.contentType with content-type header value if any
- **deprecated** — AJAX event aliases
- **fixed** — Do not execute scripts for unsuccessful HTTP responses
- **changed** — Simplify jQuery.ajaxSettings.xhr
- **changed** — Make .attr(name, false) remove for all non-ARIA attrs
- **fixed** — Don't stringify attributes in the setter
- **removed** — Drop the toggleClass(boolean|undefined) signature
- **changed** — Refactor val(): don't strip carriage return, isolate IE workarounds
- **fixed** — Fix dimensions of table col elements
- **fixed** — Make offsetHeight(true) etc. include negative margins

#### Changelog

https://blog.jquery.com/2026/01/17/jquery-4-0-0/

##### Ajax

- Don't treat array data as binary ([992a1911](https://github.com/jquery/jquery/commit/992a1911d0b6195012edc25fd5a48810d4be64b5))
- Allow `processData: true` even for binary data ([ce264e07](https://github.com/jquery/jquery/commit/ce264e0789116e37fe371503537a217c038dfae8))
- Support binary data (including FormData) ([a7ed9a7b](https://github.com/jquery/jquery/commit/a7ed9a7b6364273b1b964fd2cf9691dec2cbec6b))
- Support `headers` for script transport even when cross-domain ([#5142](https://github.com/jquery/jquery/issues/5142), [6d136443](https://github.com/jquery/jquery/commit/6d1364431b63b0d3bbe1c5fd604131f9db453396))
- Support `null` as success functions in `jQuery.get` ([#4989](https://github.com/jquery/jquery/issues/4989), [74978b7e](https://github.com/jquery/jquery/commit/74978b7e892537559850cda7332bdab8106e6354))
- Don't auto-execute scripts unless dataType provided ([#4822](https://github.com/jquery/jquery/issues/4822), [025da4dd](https://github.com/jquery/jquery/commit/025da4dd343e6734f3d3c1b4785b1548498115d8))
- Make responseJSON work for erroneous same-domain JSONP requests ([68b4ec59](https://github.com/jquery/jquery/commit/68b4ec59c8f290d680e9db4bc980655660817dd1))
- Execute JSONP error script responses ([#4771](https://github.com/jquery/jquery/issues/4771), [a1e619b0](https://github.com/jquery/jquery/commit/a1e619b03a557b47c3e26a5e74af12b63a0d5e73))
- Avoid CSP errors in the script transport for async requests ([#3969](https://github.com/jquery/jquery/issues/3969), [07a8e4a1](https://github.com/jquery/jquery/commit/07a8e4a177550025c1a08d7ac754839733943f55))
- Drop the json to jsonp auto-promotion logic ([#1799](https://github.com/jquery/jquery/issues/1799), [#3376](https://github.com/jquery/jquery/issues/3376), [e7b3bc48](https://github.com/jquery/jquery/commit/e7b3bc488d01d584262e12a7c5c25f935d0d034b))
- Overwrite s.contentType with content-type header value, if any ([#4119](https://github.com/jquery/jquery/issues/4119), [7fb90a6b](https://github.com/jquery/jquery/commit/7fb90a6beaeffe16699800f73746748f6a5cc2de))
- Deprecate AJAX event aliases, inline event/alias into deprecated ([23d53928](https://github.com/jquery/jquery/commit/23d53928f383b0e7440bf4b08b7524e6af232fad))
- Do not execute scripts for unsuccessful HTTP responses ([#4250](https://github.com/jquery/jquery/issues/4250), [50871a5a](https://github.com/jquery/jquery/commit/50871a5a85cc802421b40cc67e2830601968affe))
- Simplify jQuery.ajaxSettings.xhr ([#1967](https://github.com/jquery/jquery/issues/1967), [abdc89ac](https://github.com/jquery/jquery/commit/abdc89ac2e581392b800c0364e0f5f2b6a82cdc6))

##### Attributes

- Make `.attr( name, false )` remove for all non-ARIA attrs ([#5388](https://github.com/jquery/jquery/issues/5388), [063831b6](https://github.com/jquery/jquery/commit/063831b6378d518f9870ec5c4f1e7d5d16e04f36))
- Shave off a couple of bytes ([b40a4807](https://github.com/jquery/jquery/commit/b40a4807b604efbde51faf075d11e25441af1990))
- Don't stringify attributes in the setter ([#4948](https://github.com/jquery/jquery/issues/4948), [4250b628](https://github.com/jquery/jquery/commit/4250b628783d7bfa92ec6c5550c6e4b22fab6034))
- Drop the `toggleClass(boolean|undefined)` signature ([#3388](https://github.com/jquery/jquery/issues/3388), [a4421101](https://github.com/jquery/jquery/commit/a4421101fd6d9d7b0550210f8e8690641733dd9a))
- Refactor val(): don't strip carriage return, isolate IE workarounds ([ff281991](https://github.com/jquery/jquery/commit/ff2819911da6cbbed5ee42c35d695240f06e65e3))
- Don't set the type attr hook at all outside of IE ([9e66fe9a](https://github.com/jquery/jquery/commit/9e66fe9acf0ef27681f5a21149fc61678f791641))

##### CSS

- Fix dimensions of table `<col>` elements ([#5628](https://github.com/jquery/jquery/issues/5628), [eca2a564](https://github.com/jquery/jquery/commit/eca2a56457e1c40c071aeb3ac87efeb8bbb8013e))
- Dro

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