圓環倒計時我們經常見到，實現的方法也有很多種。但是本文將介紹一種全新的實現方式，使用SVG來實現倒計時功能。
本文主要用到了SVG的stroke-dasharray和stroke-dashoffset特性。下圖是倒計時運行效果：
SVG倒計時案例
下面說說相關的實現代碼。css實現代碼如下：
svg {
transform: rotate(-0.05deg);
}
circle {
transition: stroke-dasharray .2s;
}
.time-count-x {
line-height: 1.5;
position: relative;
}
.time-second {
position: absolute;
top: 50%; left: 0; right: 0;
margin-top: -.75em;
text-align: center;
font-size: 100px;
}
相關html代碼如下：
<div id="timeCountX" class="time-count-x">
<svg width="440" height="440" viewBox="0 0 440 440" class="center">
<defs>
<linearGradient x1="1" y1="0" x2="0" y2="0" id="gradient1">
<stop offset="0%" stop-color="#e52c5c"></stop>
<stop offset="100%" stop-color="#ab5aea"></stop>
</linearGradient>
<linearGradient x1="1" y1="0" x2="0" y2="0" id="gradient2">
<stop offset="0%" stop-color="#4352f3"></stop>
<stop offset="100%" stop-color="#ab5aea"></stop>
</linearGradient>
</defs>
<g transform="matrix(0,-1,1,0,0,440)">
<circle cx="220" cy="220" r="170" stroke-width="50" stroke="#f0f1f5" fill="none" stroke-dasharray="1069 1069"></circle>
<circle cx="220" cy="220" r="170" stroke-width="50" stroke="url('#gradient1')" fill="none" stroke-dasharray="1069 1069"></circle>
<circle cx="220" cy="220" r="170" stroke-width="50" stroke="url('#gradient2')" fill="none" stroke-dasharray="534.5 1069"></circle>
</g>
</svg>
<span id="timeSecond" class="time-second"></span>
</div>
最后是相關JavaScript代碼：
var eleCircles=document.querySelectorAll("#timeCountX circle");
var eleTimeSec=document.getElementById("timeSecond");
var perimeter=Math.PI*2*170;
var circleInit=function(){
if(eleCircles[1]){
eleCircles[1].setAttribute("stroke-dasharray","1069 1069")
}
if(eleCircles[2]){
eleCircles[2].setAttribute("stroke-dasharray",perimeter/2+" 1069")
}
eleTimeSec.innerHTML=""
};
var timerTimeCount=null;
var fnTimeCount=function(b){
if(timerTimeCount){
return
}
var b=b||10;
var a=function(){
var c=b/10;
if(eleCircles[1]){
eleCircles[1].setAttribute("stroke-dasharray",perimeter*c+" 1069")
}
if(eleCircles[2]&&b<=5){
eleCircles[2].setAttribute("stroke-dasharray",perimeter*c+" 1069")
}
if(eleTimeSec){
eleTimeSec.innerHTML=b
}
b--;
if(b<0){
clearInterval(timerTimeCount);
timerTimeCount=null;
alert("時間到！");
circleInit()
}
};
a();
timerTimeCount=setInterval(a,1000)
};
fnTimeCount();
整個案例的代碼非常少，有喜歡的朋友可以將代碼保存到html中，運行一下，體驗體驗實際效果。
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持腳本之家。
