From https://once.com/writebook

app/javascript/controllers/touch_controller.js

@@ -0,0 +1,54 @@
+import { Controller } from "@hotwired/stimulus"
+
+const SWIPE_DURATION = 1000
+const SWIPE_THRESHOLD = 30
+
+export default class extends Controller {
+  connect() {
+    this.element.addEventListener("touchstart", this.#handleTouchStart.bind(this), false)
+    this.element.addEventListener("touchend", this.#handleTouchEnd.bind(this), false)
+  }
+
+  #handleTouchStart(event) {
+    this.startX = event.touches[0].clientX
+    this.startY = event.touches[0].clientY
+    this.startTime = new Date().getTime()
+  }
+
+  #handleTouchEnd(event) {
+    this.endTime = new Date().getTime()
+
+    if (this.#isSelection || this.#exceedsDuration) return
+
+    const endX = event.changedTouches[0].clientX
+    const endY = event.changedTouches[0].clientY
+    const deltaX = Math.abs(endX - this.startX)
+    const deltaY = Math.abs(endY - this.startY)
+
+    if (deltaX > SWIPE_THRESHOLD && deltaY < SWIPE_THRESHOLD) {
+      if (this.startX > endX) {
+        this.#swipedRight()
+      } else {
+        this.#swipedLeft()
+      }
+    }
+  }
+
+  #swipedLeft() {
+    this.dispatch("swipe-left")
+  }
+
+  #swipedRight() {
+    this.dispatch("swipe-right")
+  }
+
+  get #exceedsDuration() {
+    const duration = this.endTime - this.startTime
+    return duration > SWIPE_DURATION
+  }
+
+  get #isSelection() {
+    const selection = window.getSelection()
+    return selection.toString().length > 0 && !selection.isCollapsed
+  }
+}