需求：九九乘法表
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>九九乘法表</title> <style> body { color: #333; } table { width: 900px; table-layout: fixed; /*border-collapse: collapse;*/ empty-cells: hide; } td { border: 1px solid #ccc; padding: 10px; } </style> </head> <body> <h1>九九乘法表</h1> <hr> <script> //JavaScript生成九九乘法表 document.write('<table>'); //循环 输出tr 行 for (var i = 1; i <= 9; i ++) { document.write('<tr>'); //输出 td 单元格 for (var j = 1; j <= i; j ++) { document.write(`<td>${i}×${j} = ${i * j}</td>`); } document.write('</tr>'); } document.write('</table>'); document.write('<br><br><br>'); document.write('<table>'); //循环 输出tr 行 for (var i = 9; i >= 1; i --) { document.write('<tr>'); //输出 td 单元格 for (var j = 1; j <= i; j ++) { document.write(`<td>${i}×${j} = ${i * j}</td>`); } document.write('</tr>'); } document.write('</table>'); document.write('<br><br><br>'); document.write('<table>'); //循环 输出tr 行 for (var i = 1; i <= 9; i ++) { document.write('<tr>'); //输出空的单元格 for (var m = 1; m <= (9-i); m ++) { document.write('<td></td>'); } //输出 td 单元格 for (var j = 1; j <= i; j ++) { document.write(`<td>${i}×${j} = ${i * j}</td>`); } document.write('</tr>'); } document.write('</table>'); document.write('<br><br><br>'); document.write('<table>'); //循环 输出tr 行 for (var i = 9; i >= 1; i --) { document.write('<tr>'); //输出空的单元格 for (var m = 1; m <= (9-i); m ++) { document.write('<td></td>'); } //输出 td 单元格 for (var j = 1; j <= i; j ++) { document.write(`<td>${i}×${j} = ${i * j}</td>`); } document.write('</tr>'); } document.write('</table>'); </script> </body> </html>