JS利用CANVAS 画环形进度条

<script>window.onload = function() {

var t = 99;

var oC = document.getElementById('c1');

var oGC = oC.getContext('2d');

var oB = (-90)*Math.PI/180;

var oR = (-25+t)*3.6*Math.PI/180;

function toDraw(){

var x = 200;

var y = 200;

var r = 150;

oGC.strokeStyle = '#abcdef';

oGC.lineWidth = '10';

oGC.beginPath();

oGC.arc(x,y,r,oB,oR,false);

oGC.stroke();

oGC.font = "Bold 50px Arial";

oGC.fillStyle = "#ccc"; 

oGC.textAlign = "center";

oGC.fillText(t+'%',x,y+10);

document.getElementById('num').innerHTML=t+'%';

}

toDraw();

}

</script>