代碼應該沒有出問題吧。。。

var aneObj=function()
{
?this.x=[];
?this.len=[];
}
aneObj.prototype.num=50;
aneObj.prototype.init=function()
{
?for(var i=0;i<this.num;i++)
?{
??this.x[i]=i*16+Math.random()*20;//[0,1)
??????? this.len[i]=200+Math.random()*50;
?}
}
aneObj.prototype.draw=function()
{
?ctx2.save();
?ctx2.globalAlpha=0.6;
?ctx2.lineWidth = 20;
?ctx2.lineCap = "round";
?ctx2.strockeStyle = "#de47ac";
?for(var i=0;i<this.num;i++)
?{
??//beginPath,moveTo,LineTo,strokeStyle,linWidth,LineCap,globalAlpha
??ctx2.beginPath();
??ctx2.moveTo(this.x[i],canHeight);
??ctx2.lineTo(this.x[i],canHeight - this.len[i]);
??ctx2.stroke();
?}
?ctx2.restore();
}?