在负责的项目中，有一个环形渐变读取进度的效果的需求，于是在网上查阅相关资料整理一下。
代码如下：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
</head>
<body>
<div class="donut">
<svg width="340" height="340" xmlns="http://www.w3.org/2000/svg" class="donut_svg">
<circle r="150" cy="170" cx="170" stroke-width="10" stroke="#FAFAFA" fill="none" />
<circle class="circle_bar" r="150" cy="170" cx="170" stroke-width="35" stroke="url(#linearGradient)" stroke-linejoin="round" stroke-linecap="round" fill="none"/>
<circle class="dot" fill="#FFFFFF" fill-rule="nonzero" cx="320" cy="170" r="12"></circle>
<defs>
<linearGradient x1="0%" y1="80.9878035%" x2="96.9769965%" y2="41.7547666%" id="linearGradient">
<stop stop-color="#18A6FF" offset="0%"></stop>
<stop stop-color="#32B7FF" offset="52.7095376%"></stop>
<stop stop-color="#0094F1" offset="100%"></stop>
</linearGradient>
</defs>
</svg>
<div class="donut_copy">
<div class="donut_title">
<span class="js-donut-figure"></span><span class="donut_spic">%</span>
</div>
</div>
</div>
<script type="text/javascript">
window.onload=function () {
'use strict';
var ProgressCircle = (function () {
function ProgressCircle(percent,radius,elementClass){
this._percent = percent; //百分比
this._radius = radius; //圆的半径
this._elementClass = elementClass;
}
ProgressCircle.prototype.calcDashOffset = function () {
var circumference;
circumference = Math.PI * (2 * this._radius); //计算圆圈的周长
return Math.round(circumference - this._percent / 100 * circumference); //计算圆圈要渲染的 长度！
}
//渲染进度条
ProgressCircle.prototype.createCSS = function() {
return $("." + this._elementClass + " .circle_bar").css('stroke-dashoffset', this.calcDashOffset());
};
//读取效果
ProgressCircle.prototype.updateText = function () {
$("." + this._elementClass + " .js-donut-figure")[0].innerText = this._percent;
}
ProgressCircle.prototype.init = function() {
var _this = this;
setTimeout(function(){
_this.updateText();
return _this.createCSS();
},1000);
};
return ProgressCircle;
})();
let progress = new ProgressCircle(50, 150, 'donut');
progress.init();
}
</script>
<style type="text/css" lang="scss">
*{
padding:0;
margin:0
}
.donut{
position: relative;
}
.circle_warp{
position: relative;
top: 0;
left: 0
}
.circle_bar {
stroke-dasharray: 942.4777960769379; //计算整个圆周的周长公式为Circumstance=2*PI*Radius 2*3.14*半径（此时是半径是150）
stroke-dashoffset: 942.4777960769379;
transition: stroke-dashoffset 1200ms cubic-bezier(.99,.01,.62,.94);
}
.donut_svg{
transform: rotate(-90deg);
}
.donut_copy{
text-align: center;
width: 340px;
height: 340px;
top: 40%;
left: 0;
position: absolute;
}
.donut_title{
opacity: 0;
font-size: 42px;
color: #171717;
margin-bottom: 2px;
animation: donutTitleFadeLeft 800ms 200ms cubic-bezier(.99,.01,.22,.94) forwards;
transform: translateX(0);
font-weight: bold;
}
.donut_spic{
content: "%";
animation: donutTitleFadeRight 800ms 200ms cubic-bezier(.99,.01,.22,.94) forwards;
opacity: 0;
transform: translateY(-20px);
}
.donut__text p{
font-size: 16px;
color: #AAAAAA;
}
@keyframes donutTitleFadeLeft {
from {
opacity: 0;
transform: translateX(0);
}
to {
opacity: 1;
transform: translateX(10px);
}
}
@keyframes donutTitleFadeRight {
from {
opacity: 0;
transform: translateX(-30px);
}
to {
opacity: 1;
transform: translateX(0);
}
}
</style>
</html>原文地址：根据原文思路修改的代码来实现的效果，有兴趣的可以看下
http://www.techbrood.com/zh/n...