JS实现滑动拼图验证

先看一下效果图：

设置画布滑块属性

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

设置背景图片：

图片链接地址可以自行更换

function getRandomImg() {
	return 'https://picsum.photos/300/150/?image=' + getRandomNumberByRange(0, 100)
}

CSS部分代码：

.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/?image=' + getRandomNumberByRange(0, 100)
		}

		function draw(ctx, operation, x, y) {
			ctx.beginPath()
			ctx.moveTo(x, y)
			ctx.lineTo(x + l / 2, y)
			ctx.arc(x + l / 2, y - r + 2, r, 0, 2 * PI)
			ctx.lineTo(x + l / 2, y)
			ctx.lineTo(x + l, y)
			ctx.lineTo(x + l, y + l / 2)
			ctx.arc(x + l + r - 2, y + l / 2, r, 0, 2 * PI)
			ctx.lineTo(x + l, y + l / 2)
			ctx.lineTo(x + l, y + l)
			ctx.lineTo(x, y + l)
			ctx.lineTo(x, y)
			ctx.fillStyle = '#fff'
			ctx[operation]()
			ctx.beginPath()
			ctx.arc(x, y + l / 2, r, 1.5 * PI, 0.5 * PI)
			ctx.globalCompositeOperation = "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>