[CLEANUP] Remove old browser workarounds, targeting Ember 6.x

[johanrd]

See Ember 6.x browser support: https://emberjs.com/browser-support/

Cowritten by claude

Is globalThis safe in all target environments including Node/SSR?

globalThis is supported since Chrome 71, Firefox 65, Safari 12.1, Edge 79, and Node.js 12.0.0. Ember 6.x targets Chrome >= 109, Firefox >= 115, Safari >= 15.6, Edge >= 128, Node >= 18 — all well above the minimum.

• MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/globalThis
• Can I Use: https://caniuse.com/mdn-javascript_builtins_globalthis

Popstate workaround removal — are we sure no target browser fires popstate on initial page load?

Chrome fixed this in v34 (https://bugs.chromium.org/p/chromium/issues/detail?id=63040). Firefox 'never' had the bug it seems. Safari fixed it in 9.1, see mdn/content#43368 (comment)

• MDN popstate: https://developer.mozilla.org/en-US/docs/Web/API/Window/popstate_event

event.button !== 0 vs event.which > 1 — is this a behavior change?

No. MouseEvent.button (standard, returns 0 for primary click) and UIEvent.which (deprecated, returns 1 for primary click) both correctly identify non-primary clicks in all target browsers. The old which > 1 check existed because IE9 could return undefined for which, which is irrelevant for Ember 6.x targets.

• MouseEvent.button (standard): https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/button
• UIEvent.which (deprecated): https://developer.mozilla.org/en-US/docs/Web/API/UIEvent/which

isEdge export removal — could this break addons?

It's exported from internal-test-helpers, which is a private workspace-internal package, not published to npm. The export was unused even within this repo.

• File (1 line, on main): https://github.com/emberjs/ember.js/blob/96427a6f7a/packages/internal-test-helpers/lib/browser-detect.ts
• Export site: https://github.com/emberjs/ember.js/blob/96427a6f7a/packages/internal-test-helpers/index.ts#L60

ClientRect → DOMRect type change — is this a public API?

getViewBoundingClientRect is marked @Private and is only intended for dev tools like Ember Inspector. The change is also a no-op at runtime since Range.getBoundingClientRect() already returns DOMRect in all target browsers.

• @Private annotation: https://github.com/emberjs/ember.js/blob/96427a6f7a/packages/@ember/-internals/views/lib/system/utils.ts#L199-L201

Should this target 6.x or wait for 7.0?

Should be safe for 6.x. None of these changes alter user-facing behavior — they remove dead code paths that could never execute in target browsers.

[NullVoxPopuli]

why is this test safe to remove?

[NullVoxPopuli]

I guess if we don't support the browser this was intended for? (based on the history location changes below)

[johanrd]

The test validated the _previousURL workaround (asserting this._previousURL === this.getURL() after initState). Since the workaround is removed, the property no longer exists. The underlying behavior (popstate not firing on page load) shouln't need a test — it's browser behavior, not Ember logic?

Chrome fixed it in v34 (Jan 2014): https://bugs.chromium.org/p/chromium/issues/detail?id=63040.
All Ember 6.x target browsers (Chrome >= 109, Safari >= 15.6, Firefox >= 115, Edge >= 128) are unaffected.
Manually verified on current Safari and Safari 15.3 as well with this gist

[johanrd]

But be ware that the above is my understanding of this. MDN still states that "Safari always emit a popstate event on page load" (see popstate_event#the_history_stack). I couldn't reproduce, so I did file a bug at MDN mdn/content#43368

If someone has access to older safaris (through browserstack?), it could be useful to pinpoint a version (if my gist is even valid)

[NullVoxPopuli]

I mean, this fits our minimum supported browser versions, per: https://emberjs.com/browser-support/

[johanrd]

I now tried in browserstack, and I can verify that Safari fixed this between v8.0 and 9.1, see mdn/content#43368 (comment)

[NullVoxPopuli]

why was this removed?

[johanrd]

The comment referenced an EdgeHTML bug (which is dead since Edge switched to Chromium in Jan 2020), so the comment was misleading/outdated. The setDebugFunction call from 5bbd43e is itself is kept. It could still serve well as a defensive afterEach cleanup in case callWithStub's finally block ever doesn't run? but not sure if needed

[NullVoxPopuli]

@copilot where is this used?

[NullVoxPopuli]

(also @johanrd <3)

[NullVoxPopuli]

This is used in 2 spots:
https://github.com/search?q=repo%3Aemberjs%2Fember.js+global%27&type=code

[NullVoxPopuli]

can be cleaned up later probably -- there is an IIFE here that needs some looking in to

[johanrd]

@NullVoxPopuli Good call. That would look something like this: Proposed cleanup commit: johanrd@4be5c06, full diff: https://github.com/johanrd/ember.js/pull/10/changes

It seems like a good fix, but testing it on you now, before I make it part of this PR.

[johanrd]

Included the cleanup now

[Copilot]

Pull request overview

This PR removes legacy browser workarounds and IE/old-Edge compatibility paths throughout Ember’s runtime, routing, and internal test helpers, aligning the codebase with Ember 6.x’s supported browser/runtime matrix.

Changes:

• Replace legacy global/object detection and timing fallbacks with modern primitives (globalThis, performance.now()), and remove browser-specific workarounds (IE/Edge/WebKit).
• Simplify routing/location behavior by relying on location.origin and removing the initial popstate workaround logic.
• Update test utilities and integration tests to use modern event constructors (Event, MouseEvent, KeyboardEvent) and remove old-environment conditionals.

Reviewed changes

Copilot reviewed 31 out of 31 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/loader/lib/index.js	Switch global lookup logic to rely on globalThis.
packages/internal-test-helpers/lib/system/synthetic-events.ts	Use direct MouseEvent/KeyboardEvent constructors and simplify focus checks.
packages/internal-test-helpers/lib/matchers.ts	Remove IE-specific matcher comment while keeping normalization behavior.
packages/internal-test-helpers/lib/equal-inner-html.ts	Remove IE SVG innerHTML normalization path.
packages/internal-test-helpers/lib/ember-dev/assertion.ts	Remove Edge-specific comment/workaround note in teardown.
packages/internal-test-helpers/lib/browser-detect.ts	Remove unused Edge detection helper.
packages/internal-test-helpers/index.ts	Stop exporting removed Edge detection helper.
packages/@glimmer/runtime/lib/dom/props.ts	Clarify attribute override rationale with modern DOM semantics.
packages/@ember/runloop/tests/later_test.js	Update comments to reflect modern browser behavior.
packages/@ember/routing/tests/location/util_test.js	Update mocks to use location.origin.
packages/@ember/routing/tests/location/history_location_test.js	Remove test for legacy popstate workaround.
packages/@ember/routing/tests/location/hash_location_test.js	Use new Event('hashchange') instead of legacy createEvent.
packages/@ember/routing/lib/location-utils.ts	Remove getOrigin fallback and use location.origin directly.
packages/@ember/routing/history-location.ts	Remove initial popstate workaround state tracking.
packages/@ember/object/mixin.ts	Drop IE11 WeakMap/sealed-object priming path in DEBUG.
packages/@ember/instrumentation/index.ts	Use performance.now() directly for timing.
packages/@ember/debug/index.ts	Always freeze in debugFreeze (removes old Chrome-era optimization).
packages/@ember/-internals/views/lib/system/utils.ts	Update click detection logic and modernize rect typing.
packages/@ember/-internals/metal/lib/property_get.ts	Remove IE-era guidance from docs and modernize wording.
packages/@ember/-internals/glimmer/tests/integration/syntax/each-test.js	Remove IE11 Set-construction workaround in tests.
packages/@ember/-internals/glimmer/tests/integration/event-dispatcher-test.js	Use new Event and remove conditional test gating.
packages/@ember/-internals/glimmer/tests/integration/components/utils-test.js	Update rect assertions to modern DOM types.
packages/@ember/-internals/glimmer/tests/integration/components/textarea-curly-test.js	Use new Event instead of legacy createEvent.
packages/@ember/-internals/glimmer/tests/integration/components/textarea-angle-test.js	Use new Event instead of legacy createEvent.
packages/@ember/-internals/glimmer/tests/integration/components/link-to/routing-curly-test.js	Remove URL normalization helper and assert directly on href attributes.
packages/@ember/-internals/glimmer/tests/integration/components/link-to/routing-angle-test.js	Remove URL normalization helper and modernize click event creation.
packages/@ember/-internals/glimmer/tests/integration/components/input-curly-test.js	Use new Event instead of legacy createEvent.
packages/@ember/-internals/glimmer/tests/integration/components/input-angle-test.js	Use new Event instead of legacy createEvent.
packages/@ember/-internals/environment/lib/global.ts	Replace complex global detection with globalThis + explicit Ember global typing.
packages/@ember/-internals/environment/lib/env.ts	Rely on inferred EmberENV type from global typing.
eslint.config.mjs	Add modern DOM globals for linting in packages JS files.

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