<!DOCTYPE html>
<html>
<head>
<meta charset=" utf-8">
<title>圆环进度条</title>
<style type="text/css">
circle{
-webkit-transition: stroke-dasharray .25s;
transition: stroke-dasharray .25s;
}
</style>
<script>
window.onload = function () {
if (window.addEventListener) {
var range = document.querySelector("#range");
var circle = document.querySelectorAll("circle")[1];
if (range && circle) {
range.addEventListener("change", function () {
console.log(this.value,2*Math.PI*50);
var percent = this.value / 100, lineLength = 2*Math.PI * 50;
circle.setAttribute('stroke-dasharray', lineLength* percent + " " + lineLength * (1 - percent));
});
}
}
}
</script>
</head>
<body>
<svg width="200" height="200">
<circle cx="100" cy="100" r="50" stroke-width="10" stroke="#D1D3D7" fill="none"></circle>
<circle cx="100" cy="100" r="50" stroke-width="10" stroke="#00A5E0" fill="none" stroke-dasharray="0 50">
</circle>
</svg>
<p>拖我：<input id="range" type="range" min="0" max="100" value="0" style="width:300px;"></p>
</body>
</html>