From e474ffe79c09d450b7891b28c09140030a3cae92 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 21 Feb 2024 22:49:29 -0500
Subject: [PATCH] type stuff

---
 .../src/internal/client/reactivity/computations.js       | 3 ++-
 packages/svelte/src/internal/client/transitions.js       | 9 ++++++---
 packages/svelte/src/internal/client/types.d.ts           | 7 +++++++
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/packages/svelte/src/internal/client/reactivity/computations.js b/packages/svelte/src/internal/client/reactivity/computations.js
index 926159c067..ebcd224bd8 100644
--- a/packages/svelte/src/internal/client/reactivity/computations.js
+++ b/packages/svelte/src/internal/client/reactivity/computations.js
@@ -266,6 +266,7 @@ export function derived_safe_equal(fn) {
  * @param {() => void} done
  */
 export function pause_effect(effect, done) {
+	/** @type {import('../types.js').TransitionObject[]} */
 	const transitions = [];
 
 	pause_children(effect, transitions);
@@ -291,7 +292,7 @@ export function pause_effect(effect, done) {
 
 /**
  * @param {import('../types.js').ComputationSignal} effect
- * @param {TODO[]} transitions
+ * @param {import('../types.js').TransitionObject[]} transitions
  */
 function pause_children(effect, transitions) {
 	effect.f |= INERT;
diff --git a/packages/svelte/src/internal/client/transitions.js b/packages/svelte/src/internal/client/transitions.js
index 962eb2acec..805e6e24be 100644
--- a/packages/svelte/src/internal/client/transitions.js
+++ b/packages/svelte/src/internal/client/transitions.js
@@ -516,16 +516,19 @@ export function bind_transition(element, get_fn, get_params, direction, global)
 	/** @type {Animation | null} */
 	let current_animation;
 
-	/** @type {TODO} */
+	/** @type {import('./types.js').TransitionPayload | null} */
 	let current_options;
 
 	let current_delta = 0;
 
+	/** @type {import('./types.js').TransitionObject} */
 	const transition = {
 		global,
 		to(target, callback) {
 			if (current_animation && current_options) {
-				p = current_delta * (current_animation.currentTime / current_options.duration);
+				const time = /** @type {number} */ (current_animation.currentTime);
+				const duration = /** @type {number} */ (current_options.duration);
+				p = (current_delta * time) / duration;
 				current_animation.cancel();
 			}
 
@@ -545,7 +548,7 @@ export function bind_transition(element, get_fn, get_params, direction, global)
 				current_delta = target - p;
 
 				for (let i = 0; i <= n; i += 1) {
-					const t = current_options.easing(p + (current_delta * i) / n);
+					const t = (current_options.easing ?? linear)(p + (current_delta * i) / n);
 					const css = current_options.css(t, 1 - t);
 					keyframes.push(css_to_keyframe(css));
 				}
diff --git a/packages/svelte/src/internal/client/types.d.ts b/packages/svelte/src/internal/client/types.d.ts
index 028f81af43..06b015be98 100644
--- a/packages/svelte/src/internal/client/types.d.ts
+++ b/packages/svelte/src/internal/client/types.d.ts
@@ -421,3 +421,10 @@ export interface ProxyMetadata<T = Record<string | symbol, any>> {
 export type ProxyStateObject<T = Record<string | symbol, any>> = T & {
 	[STATE_SYMBOL]: ProxyMetadata;
 };
+
+// TODO remove the other transition types once we're
+// happy we don't need them, and rename this
+export interface TransitionObject {
+	global: boolean;
+	to(target: number, callback?: () => void): void;
+}