滑块验证前端实现

ps：只是前端验证 不具备高安全性；

实现：监听滑块的移动事件，获取它离左侧的距离，赋值给分离出来的验证模块就可以了，至于陷下去的模块，得到图片的大小，根据图片的长宽的一半随机赋值吧（因为这个模块一般都在右侧靠中间的位置）

html代码：

<div class="box">
<div class="imgBox">
<div class="verify"></div>
<div class="verified"></div>
</div>
<div class="handle">
<span class="swiper"></span>
<span class="text">拖动滑块</span>
</div>
<div class="refreshBox">
<span class="refresh">点击切换图片</span>
</div>
</div>

css代码：

.box {
300px;
padding: 20px;
background-color: #fff;
box-shadow: 2px 2px 8px 0 rgba(0, 0, 0, 0.4);
}

.imgBox {
position: relative;
300px;
overflow: hidden;
box-shadow: 0 0 8px 0 rgba(0, 0, 0, 0.4);
}

.imgBox img {
100%;
height: 250px;
}

.imgBox div {
display: none;
}

.handle {
display: flex;
align-items: center;
position: relative;
height: 30px;
border-radius: 20px;
margin: 20px 0;
padding: 4px 0 4px 70px;
box-shadow: 0 0 20px 0 rgba(0, 0, 0, 0.2) inset;
background: #f5f5f5;
user-select: none;
}

.text {
opacity: 1;
transition: opacity 0.5s ease-in-out;
color: #aaa;
}

.swiper {
position: absolute;
top: -10px;
left: 0px;
58px;
height: 58px;
border-radius: 50%;
background-color: pink;
box-shadow: 2px 2px 6px 0 rgba(0, 0, 0, 0.2);
}

.verify {
position: absolute;
left: 10px;
38px;
height: 38px;
border-radius: 5px;
background-repeat: no-repeat;
background-attachment: scroll;
background-size: 300px;
box-shadow: 0 0 10px 0 rgba(0, 0, 0, 0.4), 0 0 10px 0 rgba(90, 90, 90, 0.4);
z-index: 10;
}

.verified {
position: absolute;
38px;
height: 38px;
border-radius: 5px;
background-color: rgba(0, 0, 0, 0.1);
box-shadow: 0 0 10px 0 rgba(0, 0, 0, 0.4) inset;
}

.refreshBox {
border-top: 1px solid #ccc;
padding: 15px 0 0 5px;
}

.refresh {
color: #fff;
cursor: pointer;
-webkit-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
padding: 8px 20px;
border-radius: 20px;
background-color: #555;
box-shadow: 0 0 10px 0 rgba(0, 0, 0, 0.4);
transition: all 0.5s ease-in-out;
}
.refresh.click {
box-shadow: 0 0 10px 0 rgba(0, 0, 0, 0.4) inset;
}

js代码：

var box = $('.box'),
imgBox = $('.imgBox'),
handle = $('.handle'),
swiper = $('.swiper'),
text = $('.text'),
verify = $('.verify'),
verified = $('.verified'),
refresh = $('.refresh')

// 图片集合
var imgs = []
for (let i = 1; i < 17; i++) {
imgs.push('' + i + i)
}

$(function() {
// 随机添加背景图
refreshImg()

refresh.click(function() {
e = event || window.event
e.stopPropagation()

refreshImg()
start()
})

refresh.mousedown(function() {
$(this).addClass('click')
})
refresh.mouseup(function() {
$(this).removeClass('click')
})

window.onload = start()
})

function start() {
var verImg = document.getElementsByClassName('verImg')[0]

if (verImg) {
verImg.onload = function() {
// 获取图片高度
var imgH = this.clientHeight
// 随机生成坐标（图片框固定宽度为300px，高度不定）
var verX = 150 * (1 + Math.random()) - 38,
verY = imgH / 4 + Math.random() * imgH / 2

// 用户移动滑块函数
fnDown(verX, verY)
}
}
}

function fnDown(verX, verY) {
swiper.mousedown(function() {
e = event || window.event
e.stopPropagation()

// 30为模块宽度
verify.css({
display: 'block',
top: `${verY}px`,
'background-position': `-${verX}px -${verY}px`
})
verified.css({ display: 'block', left: `${verX}px`, top: `${verY}px` })
// 获取鼠标到按钮的距离
var disX = e.clientX - $(this).offset().left,
disY = e.clientY - $(this).offset().top
text.css('opacity', '0')

// 防止重复绑定触发多次
box.unbind('mousemove')
box.unbind('mouseup')

// 移动
box.bind('mousemove', function() {
e = event || window.event
fnMove(e, disX, disY)
})

// 释放
box.bind('mouseup', function() {
var stopL = verify.offset().left - 28
// 误差在2px以内则算做成功
if (Math.abs(stopL - verX) > 2) {
alert('验证失败')
} else {
alert('验证成功')
}
// 解除绑定，并将滑动模块归位
box.unbind('mousemove')
swiper.css('left', '0px')
verify.css('left', '10px')
text.css('opacity', '1')
box.unbind('mouseup')
})
})
}

function fnMove(e, posX, posY) {
// 这里的e是以鼠标为参考
var l = e.clientX - posX - $(handle).offset().left,
winW = $(handle).width() + 29
// 限制拖动范围只能在handle中
if (l < 0) {
l = 0
} else if (l > winW) {
l = winW
}

swiper.css('left', `${l}px`)
verify.css('left', `${l + 10}px`)
}

function refreshImg() {
// 随机生成下标
var index = Math.round(Math.random() * 15)
var imgH = 0

verify.hide()
verified.hide()

var verImg = $('.verImg')
if (verImg.length) {
verImg.attr('src', `imgs/${imgs[index]}.jpg`) //imgs文件夹存放图片
} else {
imgBox.prepend(`<img class='verImg' src="imgs/${imgs[index]}.jpg" />`)
}
verify.css('background-image', `url('imgs/${imgs[index]}.jpg')`)
}

最主要的三部分有了，还要 

自己需要建一个文件夹存放图片，从中随机获取图片

我自己是imgs文件夹；