前端？ js 写个onclick 事件 修改并显示框中的值
<html>
<form>
<input type=text name=amount value=1>
<input type=button value="+" onClick="javascript:this.form.amount.value++;">
<input type=button value="-" onClick="javascript:this.form.amount.value--;">
</form>
</html>
<html>
<form>
<input type=text name=amount value=1>
<input type=button value="+" onClick="javascript:this.form.amount.value++;">
<input type=button value="-" onClick="javascript:this.form.amount.value--;">
</form>
</html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="js/jquery-1.4.2.js"></script>
<script type="text/javascript">
$(function(){
calc(); //计算方法
//全选\反选
$("#selectAll").click(function(){
var $obj =$(this).attr("checked");
if($obj){
$("input[name='ck1']").attr("checked",true);
}else{
$("input[name='ck1']").attr("checked",false);
}
}); //删除所选
$("#deleteSelete").click(function(){
$("input[name='ck1']:checked").each(function(){
$(this).parent().parent().remove();
});
calc();
});
//单击删除
$("#mytable .delete").click(function(){
$(this).parent().parent().remove();
calc()
});
//单机商品数量+
$("#mytable .add").click(function(){
//获得单前数量
var $goodsCount= parseInt($(this).prev().val());
$(this).prev().val($goodsCount+1);
calc();
});
//单机商品数量-
$("#mytable .cut").click(function(){
//获得单前数量
var $goodsCount= parseInt($(this).next().val());
$(this).next().val($goodsCount<=1?1:$goodsCount-1);
calc();
}); //计算价格
function calc(){
//找到共有对象
var $obj = $("input[name='deleteGoods']");
//var $obj = $("#mytable .delete");//也可以获得对象
var sum =0;
//循环共有对象，让它循环获得我们想要的对象的值
$obj.each(function(){
//获得商品价格
var $price = parseInt($(this).parent().prev().prev().prev().html());
//获得商品数量
var $count = parseFloat($(this).parent().prev().prev().find("input").val());
var timSum =$count*$price;
$(this).parent().prev().html("￥"+timSum);//给商品小计赋值
sum +=timSum; //累加计算总价
});
$("#sum").html(sum);
};
//绑定所有输入数量输入框的事件,输入值后自动计算
$("input[name='inputCount']").each(function(){
$(this).keyup(function(){
var num = $(this).val();
if(num!=""){
calc();
}else{
$("#mytable .cut").next().val(1); //赋一个默认数量1
calc();
}
});
});
});
</script>
<title>表单操作</title>
<style type="text/css">
.inputs{
width:20px;
}
#main{
padding:0px;
margin:0px;
position:relative;
}
#mytable{
width:400px;
}
#mytable td{
width:200px;
}
</style>
</head>
<body>
<div>
<div id="main">
<table id="mytable">
<tr>
<td>
<input type="checkbox" name="all" id="selectAll" >全选
</td>
<td>单价</td>
<td>购买个数</td>
<td>费用</td>
<td>删除</td>
</tr>
<tr>
<td><input type="checkbox" name="ck1" id="ck1"></td>
<td>123</td>
<td>
<img src="img/taobao_minus.jpg" class="cut">
<input type="text" size="4" value="1" style="width:20px" name="inputCount"/>
<img src="img/taobao_adding.jpg" class="add"></td>
<td></td>
<td><input type="button" value="删除" class="delete" name="deleteGoods"></td>
</tr>
<tr>
<td><input type="checkbox" name="ck1" id="ck2"></td>
<td>432</td>
<td>
<img src="img/taobao_minus.jpg" class="cut">
<input type="text" size="4" value="1" style="width:20px" name="inputCount"/>
<img src="img/taobao_adding.jpg" class="add"></td>
<td></td>
<td><input type="button" value="删除" class="delete" name="deleteGoods"></td>
</tr>
<tr>
<td><input type="checkbox" name="ck1" id="ck3"></td>
<td>789</td>
<td>
<img src="img/taobao_minus.jpg" class="cut">
<input type="text" size="4" value="1" style="width:20px" name="inputCount"/>
<img src="img/taobao_adding.jpg" class="add"></td>
<td></td>
<td><input type="button" value="删除" class="delete" name="deleteGoods"></td>
</tr>
<tr>
<td><input type="checkbox" name="ck1" id="ck4"></td>
<td>153</td>
<td>
<img src="img/taobao_minus.jpg" class="cut">
<input type="text" size="4" value="1" style="width:20px" name="inputCount"/>
<img src="img/taobao_adding.jpg" class="add"></td>
<td></td>
<td><input type="button" value="删除" class="delete" name="deleteGoods"></td>
</tr>
<tr><td colspan="5" align="right">总费用：<span id="sum"></span></td></tr>
<tr><td colspan="5"><input type="button" value="删除选中的项" id="deleteSelete"> </td></tr>
</table>
</div>
</div>
</body>
</html>
<input type=button value="+" onClick="javascript:this.form.amount.value++;">
<input type=button value="-" onClick="javascript:if(this.form.amount.value>1) this.form.amount.value--;">