你题目的解答代码如下:
<!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>
<table>
<tr>
<td>
<input type="button" value="-" onclick="adf('text1',-1);" />
<input type="text" id="text1" value="0" />
<input type="button" value="+" onclick="adf('text1',1);" />
</td>
</tr>
<tr>
<td>
<input type="button" value="-" onclick="adf('text2',-1);" />
<input type="text" id="text2" value="0" />
<input type="button" value="+" onclick="adf('text2',1);" />
</td>
</tr>
</table>
<script type="text/javascript">
function adf(id,n) {
var obj = document.getElementById(id);
var v = (parseInt(obj.value, 10) || 0) + n;
if (v>=0)
obj.value = v;
}
</script>
</body>
</html>
如有帮助,望采纳!谢谢!
https://blog.csdn.net/weixin_44058725/article/details/121223782?spm=1001.2014.3001.5502
参考这个