janpaepke/ScrollMagic v3.0.0-beta.1 on GitHub

scrollVelocity getter — per-container scroll velocity in px/s, shared across all instances on the same scroll parent via ContainerProxy. Returns 0 when disabled, destroyed, or idle (100ms staleness decay).
enable() / disable() — temporarily disconnect all observers without destroying the instance. Progress freezes at its current value; modify(), on()/off(), plugins, and most getters remain functional. Re-enabling reconnects everything and schedules a full recalculation.
{ once: true } event listener option — follows the DOM addEventListener options bag pattern. Works with both .on() and .subscribe().
refresh() / refreshAll() / destroyAll() — force bounds recalculation after layout changes invisible to ResizeObserver (position shifts, class toggles, sibling DOM mutations, font loading, etc.).
Post-destroy and non-browser guards — all public methods now warn in dev mode and bail cleanly instead of producing undefined behavior when called after destroy() or outside a browser environment.
Element–scrollParent ancestry validation (dev mode) — console.error when the tracked element isn't a descendant of its scroll parent, catching silent IntersectionObserver misconfiguration.

Container position not initialized synchronously — non-window containers defaulted to {top:0,left:0} until the first scroll/resize event, producing wrong initial progress for containers offset from the viewport top.
Zero-size container guard — when a scroll container collapses to 0px, updateProgress() no longer produces incorrect values (division by near-zero) and updateViewportObserver() no longer passes broken margins to the IntersectionObserver.
Direction change not invalidating elementBoundsCache — changing vertical via modify() left stale axis-dependent bounds in the cache.
containerBounds not rescheduled on option changes — triggerStart, triggerEnd, and vertical changes via modify() didn't trigger a container bounds recalculation, causing wrong progress and viewport margins.
Stale closure in onElementResize — updateElementBoundsCache() replaced the entire bounds object, but the resize handler's destructured reference pointed to the old one, so size comparisons always returned false and progress never recalculated after element resize.
destroy() skipping plugin onRemove callbacks — plugin cleanup was routed through removePlugin(), which hit the guardInert() check (destroyed was already true) and silently skipped all onRemove callbacks.

Replace debounce with throttleRaf for container resize — removes the arbitrary 100ms debounce delay. Both window and element resize paths now use rAF-batched throttling for consistent, responsive behavior.
Cache PixelConverter results — elementStart/elementEnd converters are skipped when element size is unchanged (common during scroll). Bounds caches mutated in-place via Object.assign instead of allocating new objects each frame.

Explicit type keyword on type-only imports for better tree-shaking.
New Vector type for {x, y} pairs, replacing the old ScrollDelta shape.
E2e tests reorganized from origin-based to feature-based structure. 13 regression tests covering v2-reported edge cases added.
Added MAINTAINING.md and ROADMAP.md.

npm install scrollmagic@next

See the README for full documentation.