画 浏览器页面中心 圆

    //功能：画实心圆
    //参数：圆心坐标，半径，精确度，背景颜色
    function SolidCircle(cx, cy, r, p, color) {
      var s = 1 / (r / p);
      for (var i = 0; i < Math.PI * 2; i += s) {
        var div = document.createElement("div");
        div.style.position = "absolute";
        div.style.left = Math.sin(i) * r + cx + "px";
        div.style.top = Math.cos(i) * r + cy + "px";
        div.style.width = p + "px";
        div.style.height = p + "px";
        div.style.backgroundColor = color;
        document.body.appendChild(div);
      }
    }
    winWidth = document.body.clientWidth || document.documentElement.clientWidth
    winHeight = document.body.clientHeight || document.documentElement.clientHeight
    var centers = { centerW: winWidth / 2, centerH: winHeight / 2 };
    console.log(centers)

    SolidCircle(centers.centerW, centers.centerH, 300, 2, "#0a3a87");