Day27: Click and Drag

簡介：如何使用 JavaScript 來實現點擊並拖動的效果。

作品頁面：https://iris1114.github.io/javascript30/27_Click-and-Drag/

HTML

包含一個 div 容器，內部有多個 img 元素，用於演示點擊並拖動的效果。

<!doctype html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>Click and Drag</title>
    <link rel="stylesheet" href="style.css" />
  </head>
  <body>
    <div class="items">
      <img
        src="https://source.unsplash.com/random/800x600"
        alt="Random Image"
      />
      <img
        src="https://source.unsplash.com/random/800x601"
        alt="Random Image"
      />
      <img
        src="https://source.unsplash.com/random/800x602"
        alt="Random Image"
      />
      <img
        src="https://source.unsplash.com/random/800x603"
        alt="Random Image"
      />
      <img
        src="https://source.unsplash.com/random/800x604"
        alt="Random Image"
      />
      <img
        src="https://source.unsplash.com/random/800x605"
        alt="Random Image"
      />
      <img
        src="https://source.unsplash.com/random/800x606"
        alt="Random Image"
      />
      <img
        src="https://source.unsplash.com/random/800x607"
        alt="Random Image"
      />
    </div>

    <script src="scripts.js"></script>
  </body>
</html>

CSS

設定了基本的頁面樣式，包括字體、顏色和佈局。
設置了點擊並拖動效果的樣式。

body {
  font-family: 'Arial', sans-serif;
  line-height: 1.6;
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: #f4f4f4;
}

.items {
  display: flex;
  overflow: hidden;
  border: 2px solid #333;
  width: 80%;
  cursor: grab;
}

.items img {
  max-width: 100%;
  user-select: none;
  pointer-events: none;
}

JavaScript

使用 JavaScript 來實現點擊並拖動的效果。

const slider = document.querySelector('.items')
let isDown = false
let startX
let scrollLeft

// 當滑鼠按下時觸發
slider.addEventListener('mousedown', (e) => {
  isDown = true
  slider.classList.add('active')
  startX = e.pageX - slider.offsetLeft
  scrollLeft = slider.scrollLeft
})

// 當滑鼠離開時觸發
slider.addEventListener('mouseleave', () => {
  isDown = false
  slider.classList.remove('active')
})

// 當滑鼠放開時觸發
slider.addEventListener('mouseup', () => {
  isDown = false
  slider.classList.remove('active')
})

// 當滑鼠移動時觸發
slider.addEventListener('mousemove', (e) => {
  if (!isDown) return
  e.preventDefault()
  const x = e.pageX - slider.offsetLeft
  const walk = (x - startX) * 3 // 滑動的速度
  slider.scrollLeft = scrollLeft - walk
})

Note

使用 mousedown、mouseleave、mouseup 和 mousemove 事件來實現點擊並拖動的效果。
使用 e.preventDefault() 來防止默認行為。
使用 scrollLeft 來控制滾動位置。