nodeExample/15-3.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #rect{
            position: relative;
            width: 800px;
            height: 600px;
            background-color: #fff;
        }
        .ball {
            position: absolute;
            width: 40px;
            height: 40px;
            background-color: #f22;
            border-radius: 50%;
            color: #fff;
            line-height: 40px;
            text-align: center;
        }
    </style>
</head>
<body>
    <!-- <input type="number" id='score' onchange="doCal()" onkeyup="doCal()" min='0' max="100"><br> -->
    <div id="rect"></div>
    <script>
        const rect = document.querySelector('#rect')
        let b, i, unitRad, ballNum
        ballNum = 12
        unitRad = 2* Math.PI / ballNum
        for (let i = 0; i < ballNum; i++) {
            b = document.createElement('div')
            b.className     = 'ball'
            b.style.left    = 100   +100*Math.cos(i*unitRad)+'px'
            b.style.top     = 100   +100*Math.sin(i*unitRad)+'px'
            rect.appendChild(b)
        }
        
    </script>
</body>
</html>