JavaScript-循环嵌套规律

需求

  • 要求往界面中打印 ****
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Demo</title>
    <script type="text/javascript">
        document.write("****");
    </script>
</head>
<body>
</body>
</html>


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Demo</title>
    <script type="text/javascript">
        document.write("*");
        document.write("*");
        document.write("*");
        document.write("*");
    </script>
</head>
<body>
</body>
</html>

  • 要求往界面中打印 三行、****
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Demo</title>
    <script type="text/javascript">
        for (let i = 0; i < 4; i++) {
            document.write("*");
        }
        
        document.write("<br>");
        
        for (let i = 0; i < 4; i++) {
            document.write("*");
        }
        
        document.write("<br>");
        
        for (let i = 0; i < 4; i++) {
            document.write("*");
        }
    </script>
</head>
<body>
</body>
</html>

在循环嵌套中外循环控制的是 行数, 内循环控制的是 列数。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Demo</title>
    <script type="text/javascript">
        for (let j = 0; j < 3; j++) {
         
            for (let i = 0; i < 4; i++) {
                document.write("*");
            }

            document.write("<br>");
        }
    </script>
</head>
<body>
</body>
</html>

posted @ 2021-06-30 09:48  BNTang  阅读(82)  评论(0)  编辑  收藏  举报