<head>
<meta charset="UTF-8">
<title>加减购物车</title>
<style type="text/css">
input {
width: 35px;
height: 35px;
font-size: 20px;
text-align: center;
}
</style>
<script src="js/jquery-3.3.1.min.js"></script>
<script>
$(function() {
$("input[value='-']").click(function() {
var $txt = $(this).next("input");
var num = parseInt($txt.val());
if(num - 1 >= 0) {
$txt.val(num - 1);
}
});
$("input[value='+']").click(function() {
var $txt = $(this).prev("input");
var num = parseInt($txt.val());
$txt.val(num + 1);
});
});
</script>
</head>
<body>
<p>
<input type="button" value="-" />
<input type="text" value="1" />
<input type="button" value="+" />
</p>
<p>
<input type="button" value="-" />
<input type="text" value="1" />
<input type="button" value="+" />
</p>
</body>原文：https://www.cnblogs.com/tigerlion/p/11178793.html