这个怎么写呀？想了好久都想不出

img

你题目的解答代码如下：（如有帮助，望采纳！谢谢! 点击我这个回答右上方的【采纳】按钮）

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
    <title> 页面名称 </title>
</head>
<body>

<script type="text/javascript">
for (var i = 1; i < 10; i++) {
    document.write('<hr style="border: 3px solid red; width: '+(i*50)+'px;">');
}
</script>

</body>
</html>

img

  <div id="ff" style="text-align:center;"></div>
  <script>
  for(var i=0;i<10;i++){
      var el = document.createElement('hr')
      el.style.width = (i*30 +10)+'px'
      document.getElementById('ff').appendChild(el)
  }
  </script>

img

<html lang="en">

    <head>
        <meta charset="UTF-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>Document</title>
    </head>

    <body>
        <script>
            for(var i = 1; i <= 10; i++) {
                document.body.innerHTML += "<hr style='width: " + i * 50 + "; border: none;background-color: red;height: 1px;'/>"
            }
        </script>

    </body>

</html>

效果如下
img