使用 JSON 赋能变量来执行 JS 数学运算

Question

我正在尝试执行一些 JS 数学运算以根据从 JSON 对象获取值的一系列变量来添加总值。然而，当我 运行 浏览器中的脚本时，控制台日志显示我完成了几乎一半的总和，一半只是作为一个字符串链接在一起。

如果我将以下内容粘贴到控制台中：

var sparksOfferCount = 10;
var sparksAddedOffers = 3;
var sparksUNaddedOffers = (sparksOfferCount - sparksAddedOffers); // offers that haven't been added yet
var sparksAllRewards = 0;
var sparkstotalStreakOffers = 0;
var derivedSparksTotalOffers = (sparksUNaddedOffers + sparksAllRewards + sparkstotalStreakOffers);
console.log('derived total of new offers', derivedSparksTotalOffers);

它将 return 7。但是，上面我已经用实际整数替换了对 JSON 对象的引用。当我 运行 我的代码像这样从 JSON 调用中动态获取它的值时，它在控制台中 returns '70'。奇怪，因为这意味着它能够从 10 中减去 3，然后为 sparksAllRewards 添加一个 0，但它不会为 sparkstotalStreakOffers 显示另一个 0。

var sparksSSO = JSON.parse(sessionStorage.getItem('sparksSSO')) || {};
// global variables for use with session storage
var sparksOfferCount = (sparksSSO.totalOffers >= 0) ? sparksSSO.totalOffers : "" ;
var sparksAllOffers = (sparksSSO.allOffers);
var sparksAddedOffers = (sparksSSO.totalAddedOffers);
var sparksUNaddedOffers = (sparksOfferCount - sparksAddedOffers); // offers that haven't been added yet
var sparksAllRewards = (sparksSSO.allRewards);
var sparkstotalStreakOffers = (sparksSSO.totalStreakOffers);
var derivedSparksTotalOffers = (sparksUNaddedOffers + sparksAllRewards + sparkstotalStreakOffers);
console.log('derived total of new offers from session storage', derivedSparksTotalOffers);

我很困惑。有什么想法吗？

编辑： 这是工作脚本，根据 Arthur Borba

的指导

var sparksOfferCount = (sparksSSO.totalOffers >= 0) ? sparksSSO.totalOffers : 0 ;

var sparksAllOffers = Number(sparksSSO.allOffers); 
var sparksAddedOffers = Number(sparksSSO.totalAddedOffers);
var sparksUNaddedOffers = Number(sparksOfferCount - sparksAddedOffers); // offers that haven't been added yet
var sparksAllRewards = Number(sparksSSO.allRewards);
var sparkstotalStreakOffers = Number(sparksSSO.totalStreakOffers);
var derivedSparksTotalOffers = Number(sparksUNaddedOffers + sparksAllRewards + sparkstotalStreakOffers);
console.log('derived total of new offers from session storage', derivedSparksTotalOffers);

Answer 1

尝试初始化您的计数器

var sparksOfferCount = (sparksSSO.totalOffers >= 0) ? sparksSSO.totalOffers : "" ;

带一个零（不是空字符串），像这样：

var sparksOfferCount = (sparksSSO.totalOffers >= 0) ? sparksSSO.totalOffers : 0 ;

还要检查此 Number 以确保您使用的是数字而不是字符串：

var sparksAllOffers = Number(sparksSSO.allOffers); // do it for every variable

如果这不是您想要的，请提供一些您的 JSON 数据示例。