开源实现：https://github.com/lugolabs/circles
自行实现：圆环与svg画布间剩的空间太多。
<!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="300px;"></p> </body> </html>