js-打印九九乘法表

<!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">
  <title>打印九九乘法表</title>
</head>

<body>
  <script>
    document.write(\'<table border="1" style="border-collapse:collapse">\')
    for (var i = 1; i <= 9; i++) {
      document.write(\'<tr>\')
      for (var j = 1; j <= i; j++) {
        document.write(\'<td>\' + j + \'*\' + i + \'=\' + i * j + \'</td>\')
      }
      document.write(\'</tr>\')
    }
    document.write(\'</table>\')
  </script>
</body>

</html>

js代码（打印三角形）

 <script>
    //正的直角三角形
    for (var i = 1; i <= 9; i++) {
      for (var j = 1; j <= i; j++) {
        document.write(\'★   \');

      }
      document.write(\'<br/>\');
    }

    document.write(\'<br/>\');
    document.write(\'<br/>\');
    document.write(\'<br/>\');

    // 倒的直角三角形
    // 循环的次数，for会一次执行完成
    for (var i = 1; i <= 9; i++) {
      // 每行的个数
      for (var j = i; j <= 9; j++) {
        document.write(\'★   \');

      }
      document.write(\'<br/>\');
    }
  </script>

数组冒泡排序

<!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">
  <title>数组冒泡排序</title>
</head>

<body>
  <script>
    var arr = [2, 5, 12, 21, 54, 22, 61, 6, 1, 72, 4, 1, 3, 5, 3, 51, 4, 2, 22]
      // 外层循环控制比较的轮数（length-1）
    for (var i = 0; i < arr.length - 1; i++) {
      // 外层循环控制比较的次数
      for (var j = 0; j < arr.length - 1 - i; j++) {
        // 比较大小看前一项是否大于后一项
        if (arr[j] > arr[j + 1]) {
          // 为true交互两个的值
          var temp = arr[j]
          arr[j] = arr[j + 1]
          arr[j + 1] = temp
        }
      }
    }
    console.log(arr)
  </script>
</body>

</html>