aperonight/app/javascript/controllers/counter_controller.js

import { Controller } from "@hotwired/stimulus"

export default class extends Controller {
  static values = { 
    target: Number,
    decimal: Boolean,
    duration: { type: Number, default: 2000 }
  }

  connect() {
    this.observer = new IntersectionObserver((entries) => {
      entries.forEach(entry => {
        if (entry.isIntersecting) {
          this.animate()
          this.observer.unobserve(this.element)
        }
      })
    }, { threshold: 0.5 })

    this.observer.observe(this.element)
  }

  disconnect() {
    if (this.observer) {
      this.observer.disconnect()
    }
  }

  animate() {
    const startValue = 0
    const startTime = performance.now()

    const updateCounter = (currentTime) => {
      const elapsedTime = currentTime - startTime
      const progress = Math.min(elapsedTime / this.durationValue, 1)
      
      // Easing function for smooth animation
      const easeOutQuart = 1 - Math.pow(1 - progress, 4)
      
      let currentValue = startValue + (this.targetValue - startValue) * easeOutQuart
      
      if (this.decimalValue && this.targetValue < 10) {
        currentValue = currentValue.toFixed(1)
      } else {
        currentValue = Math.floor(currentValue)
      }

      this.element.textContent = currentValue

      if (progress < 1) {
        requestAnimationFrame(updateCounter)
      } else {
        this.element.textContent = this.decimalValue && this.targetValue < 10 
          ? this.targetValue.toFixed(1) 
          : this.targetValue
      }
    }

    requestAnimationFrame(updateCounter)
  }
}