const l = 42, // 滑块边长
 r = 10, // 滑块半径
 w = 310, // canvas宽度
 h = 155, // canvas高度
 PI = Math.PI
const L = l + r * 2 // 滑块实际边长

function getRandomImg() {
 return 'https://picsum.photos/300/150/"htmlcode">

.container {
 width: 310px;
 margin: 100px auto;
}
#msg {
 width: 100%;
 line-height: 40px;
 font-size: 14px;
 text-align: center;
}
a:link,
a:visited,
a:hover,
a:active {
 margin-left: 100px;
 color: #0366D6;
}
.block {
 position: absolute;
 left: 0;
 top: 0;
}
.sliderContainer {
 position: relative;
 text-align: center;
 width: 310px;
 height: 40px;
 line-height: 40px;
 margin-top: 15px;
 background: #f7f9fa;
 color: #45494c;
 border: 1px solid #e4e7eb;
}
.sliderContainer_active .slider {
 height: 38px;
 top: -1px;
 border: 1px solid #1991FA;
}
.sliderContainer_active .sliderMask {
 height: 38px;
 border-width: 1px;
}
.sliderContainer_success .slider {
 height: 38px;
 top: -1px;
 border: 1px solid #52CCBA;
 background-color: #52CCBA !important;
}
.sliderContainer_success .sliderMask {
 height: 38px;
 border: 1px solid #52CCBA;
 background-color: #D2F4EF;
}
.sliderContainer_success .sliderIcon {
 background-position: 0 0 !important;
}
.sliderContainer_fail .slider {
 height: 38px;
 top: -1px;
 border: 1px solid #f57a7a;
 background-color: #f57a7a !important;
}
.sliderContainer_fail .sliderMask {
 height: 38px;
 border: 1px solid #f57a7a;
 background-color: #fce1e1;
}
.sliderContainer_fail .sliderIcon {
 background-position: 0 -83px !important;
}
.sliderContainer_active .sliderText,
.sliderContainer_success .sliderText,
.sliderContainer_fail .sliderText {
 display: none;
}
.sliderMask {
 position: absolute;
 left: 0;
 top: 0;
 height: 40px;
 border: 0 solid #1991FA;
 background: #D1E9FE;
}
.slider {
 position: absolute;
 top: 0;
 left: 0;
 width: 40px;
 height: 40px;
 background: #fff;
 box-shadow: 0 0 3px rgba(0, 0, 0, 0.3);
 cursor: pointer;
 transition: background .2s linear;
}
.slider:hover {
 background: #1991FA;
}
.slider:hover .sliderIcon {
 background-position: 0 -13px;
}
.sliderIcon {
 position: absolute;
 top: 15px;
 left: 13px;
 width: 14px;
 height: 10px;
 background: url(img/tb.png) 0 -26px;
 background-size: 34px 471px;
}
.refreshIcon {
 position: absolute;
 right: 0;
 top: 0;
 width: 34px;
 height: 34px;
 cursor: pointer;
 background: url(img/tb.png) 0 -437px;
 background-size: 34px 471px;
}




页面，页面只用放一个div就可以了


<div class="container">
 <div id="captcha" style="position: relative"></div>
</div>




js部分代码，包括验证是否正确


<script type="text/javascript">
 (function(window) {
 const l = 42, // 滑块边长
  r = 10, // 滑块半径
  w = 310, // canvas宽度
  h = 155, // canvas高度
  PI = Math.PI
 const L = l + r * 2 // 滑块实际边长
 function getRandomNumberByRange(start, end) {
  return Math.round(Math.random() * (end - start) + start)
 }
 function createCanvas(width, height) {
  const canvas = createElement('canvas')
  canvas.width = width
  canvas.height = height
  return canvas
 }
 function createImg(onload) {
  const img = createElement('img')
  img.crossOrigin = "Anonymous"
  img.onload = onload
  img.onerror = () => {
  img.src = getRandomImg()
  }
  img.src = getRandomImg()
  return img
 }
 function createElement(tagName) {
  return document.createElement(tagName)
 }
 function addClass(tag, className) {
  tag.classList.add(className)
 }
 function removeClass(tag, className) {
  tag.classList.remove(className)
 }
 function getRandomImg() {
  return 'https://picsum.photos/300/150/"xor"
  ctx.fill()
 }
 function sum(x, y) {
  return x + y
 }
 function square(x) {
  return x * x
 }
 class jigsaw {
  constructor(el, success, fail) {
  this.el = el
  this.success = success
  this.fail = fail
  }
  init() {
  this.initDOM()
  this.initImg()
  this.draw()
  this.bindEvents()
  }
  initDOM() {
  const canvas = createCanvas(w, h) // 画布
  const block = canvas.cloneNode(true) // 滑块
  const sliderContainer = createElement('div')
  const refreshIcon = createElement('div')
  const sliderMask = createElement('div')
  const slider = createElement('div')
  const sliderIcon = createElement('span')
  const text = createElement('span')
  block.className = 'block'
  sliderContainer.className = 'sliderContainer'
  refreshIcon.className = 'refreshIcon'
  sliderMask.className = 'sliderMask'
  slider.className = 'slider'
  sliderIcon.className = 'sliderIcon'
  text.innerHTML = '向右滑动滑块填充拼图'
  text.className = 'sliderText'
  const el = this.el
  el.appendChild(canvas)
  el.appendChild(refreshIcon)
  el.appendChild(block)
  slider.appendChild(sliderIcon)
  sliderMask.appendChild(slider)
  sliderContainer.appendChild(sliderMask)
  sliderContainer.appendChild(text)
  el.appendChild(sliderContainer)
  Object.assign(this, {
   canvas,
   block,
   sliderContainer,
   refreshIcon,
   slider,
   sliderMask,
   sliderIcon,
   text,
   canvasCtx: canvas.getContext('2d'),
   blockCtx: block.getContext('2d')
  })
  }
  initImg() {
  const img = createImg(() => {
   this.canvasCtx.drawImage(img, 0, 0, w, h)
   this.blockCtx.drawImage(img, 0, 0, w, h)
   const y = this.y - r * 2 + 2
   const ImageData = this.blockCtx.getImageData(this.x, y, L, L)
   this.block.width = L
   this.blockCtx.putImageData(ImageData, 0, y)
  })
  this.img = img
  }
  draw() {
  // 随机创建滑块的位置
  this.x = getRandomNumberByRange(L + 10, w - (L + 10))
  this.y = getRandomNumberByRange(10 + r * 2, h - (L + 10))
  draw(this.canvasCtx, 'fill', this.x, this.y)
  draw(this.blockCtx, 'clip', this.x, this.y)
  }
  clean() {
  this.canvasCtx.clearRect(0, 0, w, h)
  this.blockCtx.clearRect(0, 0, w, h)
  this.block.width = w
  }
  bindEvents() {
  this.el.onselectstart = () => false
  this.refreshIcon.onclick = () => {
   this.reset()
  }
  let originX, originY, trail = [],
   isMouseDown = false
  this.slider.addEventListener('mousedown', function(e) {
   originX = e.x, originY = e.y
   isMouseDown = true
  })
  document.addEventListener('mousemove', (e) => {
   if(!isMouseDown) return false
   const moveX = e.x - originX
   const moveY = e.y - originY
   if(moveX < 0 || moveX + 38 >= w) return false
   this.slider.style.left = moveX + 'px'
   var blockLeft = (w - 40 - 20) / (w - 40) * moveX
   this.block.style.left = blockLeft + 'px'
   addClass(this.sliderContainer, 'sliderContainer_active')
   this.sliderMask.style.width = moveX + 'px'
   trail.push(moveY)
  })
  document.addEventListener('mouseup', (e) => {
   if(!isMouseDown) return false
   isMouseDown = false
   if(e.x == originX) return false
   removeClass(this.sliderContainer, 'sliderContainer_active')
   this.trail = trail
   const {
   spliced,
   TuringTest
   } = this.verify()
   if(spliced) {
   if(TuringTest) {
    addClass(this.sliderContainer, 'sliderContainer_success')
    this.success && this.success()
   } else {
    addClass(this.sliderContainer, 'sliderContainer_fail')
    this.text.innerHTML = '再试一次'
    this.reset()
   }
   } else {
   alert("验证失败");
   addClass(this.sliderContainer, 'sliderContainer_fail')
   this.fail && this.fail();
                        //验证失败后，1秒后重新加载图片
   setTimeout(() => {
    this.reset()
   }, 1000)
   }
  })
  }
  verify() {
  const arr = this.trail // 拖动时y轴的移动距离
  const average = arr.reduce(sum) / arr.length // 平均值
  const deviations = arr.map(x => x - average) // 偏差数组
  const stddev = Math.sqrt(deviations.map(square).reduce(sum) / arr.length) // 标准差
  const left = parseInt(this.block.style.left)
  return {
   spliced: Math.abs(left - this.x) < 10,
   TuringTest: average !== stddev, // 只是简单的验证拖动轨迹，相等时一般为0，表示可能非人为操作
  }
  }
  reset() {
  this.sliderContainer.className = 'sliderContainer'
  this.slider.style.left = 0
  this.block.style.left = 0
  this.sliderMask.style.width = 0
  this.clean()
  this.img.src = getRandomImg()
  this.draw()
  }
 }
 window.jigsaw = {
  init: function(element, success, fail) {
  new jigsaw(element, success, fail).init()
  }
 }
 }(window))
 jigsaw.init(document.getElementById('captcha'), function() {
 alert("验证成功");
 })
</script>




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