Implement #1091.

packages/embla-carousel-docs/src/content/pages/api/methods.mdx

@@ -322,10 +322,10 @@ Scroll to the previous scroll snap if possible. When [loop](/api/options/#loop)
 
 ### scrollToSnap
 
-Parameters: <BrandPrimaryText>`index: number`, `jump?: boolean`</BrandPrimaryText>  
+Parameters: <BrandPrimaryText>`index: number`, `jump?: boolean`, `direction?: 'forward' | 'backward'`</BrandPrimaryText>  
 Returns: <BrandSecondaryText>`void`</BrandSecondaryText>
 
-Scroll to a scroll snap by its unique index. If [loop](/api/options/#loop) is enabled, Embla Carousel will choose the closest way to the target scroll snap. Set the **jump** parameter to `true` when you want to go to the desired scroll snap instantly.
+Scroll to a scroll snap by its unique index. Set the **jump** parameter to `true` when you want to go to the desired scroll snap instantly. If [loop](/api/options/#loop) is enabled and the **direction** parameter is omitted, Embla Carousel will choose the closest way to the target scroll snap.
 
 <Admonition type="note">
   **Note:** A scroll snap isn't equvialent to a slide. A scroll snap can hold
@@ -339,10 +339,10 @@ Scroll to a scroll snap by its unique index. If [loop](/api/options/#loop) is en
 
 ### scrollToSlide
 
-Parameters: <BrandPrimaryText>`subject: number | HTMLElement`, `jump?: boolean`</BrandPrimaryText>  
+Parameters: <BrandPrimaryText>`subject: number | HTMLElement`, `jump?: boolean`, `direction?: 'forward' | 'backward'`</BrandPrimaryText>  
 Returns: <BrandSecondaryText>`void`</BrandSecondaryText>
 
-Scroll to a scroll snap by providing a slide index or a slide element. The carousel will scroll to the scroll snap that holds the provided slide. If [loop](/api/options/#loop) is enabled, Embla Carousel will choose the closest way to the target scroll snap. Set the **jump** parameter to `true` when you want to go to the desired scroll snap instantly.
+Scroll to a scroll snap by providing a slide index or a slide element. The carousel will scroll to the scroll snap that holds the provided slide. Set the **jump** parameter to `true` when you want to go to the desired scroll snap instantly. If [loop](/api/options/#loop) is enabled and the **direction** parameter is omitted, Embla Carousel will choose the closest way to the target scroll snap.
 
 ---
 

packages/embla-carousel/src/components/EmblaCarousel.ts

@@ -7,6 +7,7 @@ import { OptionsHandler } from './OptionsHandler'
 import { PluginsHandler } from './PluginsHandler'
 import { EmblaPluginsType, EmblaPluginType } from './Plugins'
 import { isNumber, isString, WindowType } from './utils'
+import { ScrollToDirectionType } from './ScrollTo'
 
 export type EmblaCarouselType = {
   canScrollNext: () => boolean
@@ -28,12 +29,20 @@ export type EmblaCarouselType = {
   scrollPrev: (jump?: boolean) => void
   scrollProgress: () => number
   snapList: () => number[]
-  scrollToSnap: (index: number, jump?: boolean) => void
-  scrollToSlide: (subject: number | HTMLElement, jump?: boolean) => void
   selectedSnap: () => number
   slideNodes: () => HTMLElement[]
   slidesInView: () => number[]
   slidesNotInView: () => number[]
+  scrollToSnap: (
+    index: number,
+    jump?: boolean,
+    direction?: ScrollToDirectionType
+  ) => void
+  scrollToSlide: (
+    subject: number | HTMLElement,
+    jump?: boolean,
+    direction?: ScrollToDirectionType
+  ) => void
 }
 
 function EmblaCarousel(
@@ -168,19 +177,19 @@ function EmblaCarousel(
   function scrollToSnap(
     index: number,
     jump?: boolean,
-    direction?: number
+    direction?: ScrollToDirectionType
   ): void {
     if (!options.active || destroyed) return
     engine.scrollBody
       .useBaseFriction()
       .useDuration(jump === true ? 0 : options.duration)
-    engine.scrollTo.index(index, direction || 0)
+    engine.scrollTo.index(index, direction)
   }
 
   function scrollToSlide(
     subject: number | HTMLElement,
     jump?: boolean,
-    direction?: number
+    direction?: ScrollToDirectionType
   ): void {
     const index = isNumber(subject) ? subject : slides.indexOf(subject)
     const snapIndex = engine.slideRegistry.findIndex((g) => g.includes(index))

packages/embla-carousel/src/components/ScrollTarget.ts

@@ -1,4 +1,5 @@
 import { LimitType } from './Limit'
+import { DirectionType } from './ScrollTo'
 import { Vector1DType } from './Vector1d'
 import { arrayLast, mathAbs, mathSign } from './utils'
 
@@ -8,9 +9,9 @@ export type TargetType = {
 }
 
 export type ScrollTargetType = {
-  byIndex: (target: number, direction: number) => TargetType
+  byIndex: (target: number, direction: DirectionType) => TargetType
   byDistance: (force: number, snap: boolean) => TargetType
-  shortcut: (target: number, direction: number) => number
+  shortcut: (target: number, direction: DirectionType) => number
 }
 
 export function ScrollTarget(
@@ -36,7 +37,7 @@ export function ScrollTarget(
     return { index, distance }
   }
 
-  function shortcut(target: number, direction: number): number {
+  function shortcut(target: number, direction: DirectionType): number {
     const targets = [target, target + contentSize, target - contentSize]
 
     if (!loop) return target
@@ -47,7 +48,7 @@ export function ScrollTarget(
     return arrayLast(targets) - contentSize
   }
 
-  function byIndex(index: number, direction: number): TargetType {
+  function byIndex(index: number, direction: DirectionType): TargetType {
     const diffToSnap = scrollSnaps[index] - targetVector.get()
     const distance = shortcut(diffToSnap, direction)
     return { index, distance }

packages/embla-carousel/src/components/ScrollTo.ts

@@ -4,10 +4,14 @@ import { EventHandlerType } from './EventHandler'
 import { ScrollBodyType } from './ScrollBody'
 import { ScrollTargetType, TargetType } from './ScrollTarget'
 import { Vector1DType } from './Vector1d'
+import { isNumber } from './utils'
+
+export type DirectionType = 0 | 1 | -1
+export type ScrollToDirectionType = 'forward' | 'backward' | DirectionType
 
 export type ScrollToType = {
   distance: (n: number, snap: boolean) => void
-  index: (n: number, direction: number) => void
+  index: (n: number, direction?: ScrollToDirectionType) => void
 }
 
 export function ScrollTo(
@@ -47,12 +51,18 @@ export function ScrollTo(
     scrollTo(target)
   }
 
-  function index(n: number, direction: number): void {
-    const targetIndex = indexCurrent.clone().set(n)
-    const target = scrollTarget.byIndex(targetIndex.get(), direction)
+  function index(n: number, direction?: ScrollToDirectionType): void {
+    const targetIndex = indexCurrent.clone().set(n).get()
+    const target = scrollTarget.byIndex(targetIndex, getDirection(direction))
     scrollTo(target)
   }
 
+  function getDirection(direction?: ScrollToDirectionType): DirectionType {
+    if (!direction) return 0
+    if (isNumber(direction)) return direction
+    return direction === 'forward' ? -1 : 1
+  }
+
   const self: ScrollToType = {
     distance,
     index