本文实例讲述了原生js实现的移动端可拖动进度条插件功能。分享给大家供大家参考，具体如下：
该插件最初的想法来自网上的一篇文章，直达链接：//www.jb51.net/article/167717.htm
笔者因为业务需要寻找到这个插件，然后拿来用之，发现各种不方便，然后便开始了改造之路。
上代码：
<script>
function dragSlide(id) {
this.minDiv =document.getElementById(id); //小方块
this.width = parseInt(window.getComputedStyle(this.minDiv, null).width); //小方块的宽度
this.lineDiv = this.minDiv.parentNode; //长线条
//滑动的数值呈现
this.vals = this.minDiv.children[0];
var that=this;
var move = function(e) {
var x = e.touches[0].pageX;
var lineDiv_left = that.getPosition(that.lineDiv).left; //长线条的横坐标
var minDiv_left = x - lineDiv_left; //小方块相对于父元素（长线条）的left值
if (minDiv_left >= that.lineDiv.offsetWidth - that.width) {
minDiv_left = that.lineDiv.offsetWidth - that.width;
}
if (minDiv_left <0 ) {
minDiv_left = 0;
}
//设置拖动后小方块的left值
that.minDiv.style.left = minDiv_left + "px";
//percent百分比改为如下所示,解决开始和最后滑动的体验不好问题
var percent = (minDiv_left / (that.lineDiv.offsetWidth - that.width)) * 100;
if (percent > 0 && percent < 0.5) {
percent = Math.ceil(percent);
} else {
percent = Math.floor(percent);
}
that.vals.innerText = percent;
}
//获取元素的绝对位置,工具函数
this.getPosition = function(node) {
var left = node.offsetLeft; //获取元素相对于其父元素的left值var left
var top = node.offsetTop;
current = node.offsetParent; // 取得元素的offsetParent
// 一直循环直到根元素
while (current != null) {
left += current.offsetLeft;
top += current.offsetTop;
current = current.offsetParent;
}
return {
"left": left,
"top": top
};
}
this.minDiv.addEventListener("touchmove", move);
}
var drag0 = new dragSlide("minDiv");
var drag1 = new dragSlide("minDiv1");
//取消移动端手势长按弹出提示框的操作
document.addEventListener('contextmenu', function(e) {
e.preventDefault();
});
</script>
html和css部分没有改动，而js改动还是很大的，比较原来作者的文章，改动点如下
1）整体上，原来不是插件，改造之后成为一个可以复用的插件，虽然简单了点
2）只是将其改造为适用于移动端的插件
3）通过对开始滑动和结束滑动比例的处理，优化了开始滑动和结束滑动的体验
4）移动端加了防止长按弹出提示框的代码
5）小滑块的宽度改为动态
改造之后的整体案例，需要指出：笔者主要用在微信端，至于其他浏览器滑块的体验不是很好，还有滑块滑动体验跟小块的尺寸有直接关系。
<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=1,user-scalable=no" />
<title>鼠标拖动小方块</title>
<style type="text/css">
.lineDiv {
position: relative;
height: 5px;
background: red;
width: 300px;
margin: 50px auto;
}
.lineDiv .minDiv {
position: absolute;
top: -12.5px;
left: 0;
width: 30px;
height: 30px;
background: green;
cursor: pointer
}
.lineDiv .minDiv .vals {
position: absolute;
font-size: 20px;
top: -45px;
left: -2.5px;
width: 35px;
height: 35px;
line-height: 35px;
text-align: center;
background: blue;
}
.lineDiv .minDiv .vals:after {
content: "";
width: 0px;
height: 0px;
border-top: 6px solid blue;
border-left: 6px solid transparent;
border-right: 6px solid transparent;
border-bottom: 6px solid transparent;
display: block;
margin-left: 11px;
}
* {
-webkit-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
}
</style>
</head>
<body>
<center>
<h3>用鼠标拖动小方块<span id="msg">0</span>%</h3>
</center>
<div id="lineDiv" class="lineDiv">
<div id="minDiv" class="minDiv">
<div id="vals" class="vals">0</div>
</div>
</div>
<div style="height: 20px;"></div>
<div id="lineDiv" class="lineDiv">
<div id="minDiv1" class="minDiv">
<div id="vals" class="vals">0</div>
</div>
</div>
<script>
//避免默认事件 2018.7.10 更新 优化uc浏览器左右滑动时候页面被拖动
document.addEventListener('touchmove', function(e) {
e.preventDefault();
}, { passive: false });
function dragSlide(id) {
this.minDiv = document.getElementById(id); //小方块
this.width = parseInt(window.getComputedStyle(this.minDiv, null).width); //小方块的宽度
this.lineDiv = this.minDiv.parentNode; //长线条
//滑动的数值呈现
this.vals = this.minDiv.children[0];
var that = this;
var lastX = null; //判断鼠标移动方向，解决向左侧滑动时候的bug
var move = function(e) {
var x = e.touches[0].pageX,
direction = '';
if (lastX == null) {
lastX = x;
return;
}
if (x > lastX) {
direction = 'right';
} else if (x < lastX) {
direction = 'left';
} else {
direction = '';
}
var lineDiv_left = that.getPosition(that.lineDiv).left; //长线条的横坐标
var minDiv_left = x - lineDiv_left; //小方块相对于父元素（长线条）的left值
if (minDiv_left >= that.lineDiv.offsetWidth - that.width) {
minDiv_left = that.lineDiv.offsetWidth - that.width;
}
if (minDiv_left < 0) {
minDiv_left = 0;
}
//设置拖动后小方块的left值
that.minDiv.style.left = minDiv_left + "px";
//percent百分比改为如下所示,解决开始和最后滑动的体验不好问题
var percent = (minDiv_left / (that.lineDiv.offsetWidth - that.width)) * 100;
if (percent < 0.5 && direction == 'right') {
percent = Math.ceil(percent);
} else if (percent > 0.5 && direction == 'right') {
percent = Math.floor(percent);
} else {
percent = Math.ceil(percent);
}
that.vals.innerText = percent;
}
//获取元素的绝对位置,工具函数
this.getPosition = function(node) {
var left = node.offsetLeft; //获取元素相对于其父元素的left值var left
var top = node.offsetTop;
current = node.offsetParent; // 取得元素的offsetParent
// 一直循环直到根元素
while (current != null) {
left += current.offsetLeft;
top += current.offsetTop;
current = current.offsetParent;
}
return {
"left": left,
"top": top
};
}
this.minDiv.addEventListener("touchmove", move);
}
var drag0 = new dragSlide("minDiv");
var drag1 = new dragSlide("minDiv1");
//取消移动端手势长按弹出提示框的操作
document.addEventListener('contextmenu', function(e) {
e.preventDefault();
});
</script>
</body>
</html>
感兴趣的朋友可以使用在线HTML/CSS/JavaScript代码运行工具：http://tools.jb51.net/code/HtmlJsRun测试上述代码运行效果。
更多关于JavaScript相关内容可查看本站专题：《JavaScript页面元素操作技巧总结》、《JavaScript操作DOM技巧总结》、《JavaScript切换特效与技巧总结》、《JavaScript动画特效与技巧汇总》、《JavaScript错误与调试技巧总结》、《JavaScript数据结构与算法技巧总结》及《JavaScript数学运算用法总结》
希望本文所述对大家JavaScript程序设计有所帮助。