Question

在这里，sums [i] .value得到了正确的值，但是当我想保留所有Sum的总和时，它就失败了。

function calc() {
        var amounts = document.getElementsByName("Amount");
        var prices = document.getElementsByName("Price");
        var sums = document.getElementsByName('Sum');
        var tax = document.getElementsByName('Tax');
        var total = document.getElementsByName('Total');

        for (var i = 0; i < amounts.length; i++) {
            sums[i].value = amounts[i].value * prices[i].value;
            total[0].value = total[0].value + sums[i].value;
            // only this line is not working
        }

    }

Answer 1

纯HTML是字符串，一直向下，var amounts = document.getElementsByName("Amount");后跟amounts.value表示您现在有字符串值。由于+也是一个字符串运算符，JavaScript很乐意将"2"+"4"转换为“24”，这看起来像数学一样，但是错误的，实际上它根本就没有数学运算。

首先将所有需要数字的值转换为数字：

var amounts = document.getElementsByName("Amount");
....
var amount = parseFloat(amounts.value); // NOW it's a number
...

Answer 2

用以下代码替换您的代码：

for (var i = 0; i < amounts.length; i++) {
    sums[i].value = parseFloat(amounts[i].value) * parseFloat(prices[i].value);
    total[0].value = parseFloat(total[0].value) + parseFloat(sums[i].value);
    // only this line is not working
}

Answer 3

sums[i].value = parseFloat(amounts[i].value) * parseFloat(prices[i].value);
total[0].value = parseFloat(total[0].value) + parseFloat(sums[i].value);

这应该对你有帮助。

Answer 4

添加和乘以

时删除.value

function test()
    {
var amounts = new Array();
amounts[0] = "4";
amounts[1] = "6";
amounts[2] = "10";
var prices = new Array();
prices[0] = "4";
prices[1] = "6";
prices[2] = "10";
      var sums = new Array();
      var total = 0;

        for (var i = 0; i < amounts.length; i++) {
              sums[i] = parseInt(amounts[i]) * parseInt(prices[i]);
              total= parseInt(total) + parseInt(sums[i]);
            // only this line is not working

//alert(total); is 152
           }
    }

我想将字段Sum中的所有值添加到字段Total中，但它不起作用

4 个答案: