jquery 加减

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>jQuery 加减示例</title>
    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
</head>
<body>
    <input type="text" id="counter" value="0">
    <button id="add">加</button>
    <button id="subtract">减</button>

    <script>
        $(document).ready(function() {
            $('#add').click(function() {
                var currentValue = parseInt($('#counter').val());
                $('#counter').val(currentValue + 1);
            });

            $('#subtract').click(function() {
                var currentValue = parseInt($('#counter').val());
                $('#counter').val(currentValue - 1);
            });
        });
    </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>jQuery 样式加减示例</title>
    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
    <style>
        #box {
            width: 100px;
            height: 100px;
            background-color: red;
        }
    </style>
</head>
<body>
    <div id="box"></div>
    <button id="increase">增加宽度</button>
    <button id="decrease">减少宽度</button>

    <script>
        $(document).ready(function() {
            $('#increase').click(function() {
                var currentWidth = parseInt($('#box').css('width'));
                $('#box').css('width', currentWidth + 10 + 'px');
            });

            $('#decrease').click(function() {
                var currentWidth = parseInt($('#box').css('width'));
                $('#box').css('width', currentWidth - 10 + 'px');
            });
        });
    </script>
</body>
</html>