Question

用JS代码怎么实现两个文本框的Value相乘？

<tr>
<td colspan="2" align="center">商品名称</td>
<td colspan="2" align="center">个数</td>
<td colspan="2" align="center">单价</td>
<td colspan="2" width="347" align="center"> 总金额</td>
</tr>
<tr>
<td colspan="2" align="center"><select><option></option></select></td>
<td colspan="2" align="center"><input id="geshu" name="" type="text" size="25" value="2" onblur="totalprice()"/><span id="geshu2"></span></td>
<td colspan="2" align="center"><input id="danjia" name="" type="text" size="25" value="2" onblur="totalprice()"/><span id="danjia2"></span></td>
<td colspan="2" align="center"><div id="total"></div></td>
</tr>

就是输完单价和数量后总金额直接显示。。

Answer 1

num1 = document.getElementById('input1').value;//获取第一个文本框的值
num2 = document.getElementById('input2').value;//获取第二个文本框的值
alert(parseInt(num1)*parseInt(num2));//计算乘积并弹出
这种是简单的，复杂些的，是先判断是不是数字，是的话再计算，不是的话会提示错误的。

Answer 2

<tr>
<td colspan="2" align="center">商品名称</td>
<td colspan="2" align="center">个数</td>
<td colspan="2" align="center">单价</td>
<td colspan="2" width="347" align="center"> 总金额</td>
</tr>
<tr>
<td colspan="2" align="center"><select><option></option></select></td>
<td colspan="2" align="center"><input id="geshu" name="" type="text" size="25" value="2" onblur="totalprice()"/><span id="geshu2"></span></td>
<td colspan="2" align="center"><input id="danjia" name="" type="text" size="25" value="2" onblur="totalprice()"/><span id="danjia2"></span></td>
<td colspan="2" align="center"><div id="total"></div></td>
</tr>
<script>
function getTotal(){
var total=parseInt(document.getElementById('geshu').value)*parseInt(document.getElementById('danjia').value);
document.getElementById('total').innerHTML=total;
}
getTotal();
document.getElementById('geshu').onfocusout=function(){getTotal();}
document.getElementById('danjia').onfocusout=function(){getTotal();}
</script>

Answer 3

function totalprice(){
var num = document.getElementById("geshu").value;
var price= document.getElementById("danjia").value;
var total = document.getElementById("total");
var totalMoney = 0;
if(num!=""&&price!=""){//这里最好再做个数字和金额的校验
totalMoney = num*price;
}
total.innerHTML = totalMoney ;
}