javascript - 停止javascript自动从十进制转换为字符串

Question

我有以下代码:

if(netAnnualBilling == null){
                        netAnnualBilling = 0;
                        parseFloat(netAnnualBilling);
                }
                parseFloat(netAnnualBilling);
                annualBillingCount = (annualBillingCount + netAnnualBilling);
                parseFloat(annualBillingCount);

我的两个变量 netAnnualBilling 和 annualBillingCount 都是数字类型。但是，当我到达这一行时:

            annualBillingCount = (annualBillingCount + netAnnualBilling);

javascript 似乎将 annualBillingCount 转换为 String 类型并将两个数字附加在一起，而不是像它应该的那样添加或减去。示例:

annualBillingCount = 0; 
netAnnualBilling = -1403.30
The result of the above code will show annualBillingCount to be equal to : 0-1403.80 

每次弹出这些变量时，我都尝试过 ParseFloat，但我没有任何运气。怎么回事？

Answer 1

如果您想确保变量用作数字，您可以简单地在前面加上一元加号运算符:

annualBillingCount = +annualBillingCount + +netAnnualBilling;

将强制每个操作数被视为一个数字。

编辑 Heres a basic fiddle使用下面的代码显示了两个字符串的不同使用一元转换的添加:

var onetwo = "12";
var threefour = "34";

alert(onetwo + threefour); // string + string, so "12" + "34" = "1234"
alert(+onetwo + threefour); // number + string, so 12 + "34" = "12" + "34" = "1234"
alert(onetwo + +threefour); // string + number, second will be coerced back to string, so "12" + "34" = "1234"
alert(+onetwo + +threefour); // number + number, so 12 + 34 = 46