保存并加载日期localstorage [英] Save and load date localstorage

问题描述

我必须将日期保存到localStorage，当页面刷新时我想计算自那时起已经过了多长时间。

I have to save a date to localStorage and when the page is refreshed I want to calculate how much time has passed since then.

现在，问题出在这里： localStorage将日期保存为字符串，因此在localStorage中保存之后，尝试计算这两个日期之间的差异返回NaN。

Now, here's the problem: localStorage saves the date as a string so after it is saved in localStorage trying to calculate the difference between those two dates returns NaN.

在javascript控制台中尝试：

Try this in your javascript console:

var a = new Date();
var b = new Date();
console.log(b - a); //this works
localStorage.a = a;
localStorage.b = b;
console.log(localStorage.b - localStorage.a); //this doesn't work

我也试过 JSON.stringify 和 JSON.parse 试图保持日期对象不变，但这也不起作用。

I also tried JSON.stringify and JSON.parse trying to keep the date object intact, but that doesn't work either.

我的猜测是我必须在localStorage中解析日期。如果没有更好的方法，我该怎么做？

My guess is that I have to parse the date in the localStorage. If there is not a better method, how can I do that?

推荐答案

演示： http://jsfiddle.net/AuhtS/

代码：

var a = new Date();
var b = new Date();
console.log(b - a); //this works
localStorage.a = a;
localStorage.b = b;
a = Date.parse(localStorage.a); // parse to date object
b = Date.parse(localStorage.b);
console.log(b - a); // now, this will work

原因

所有内容都存储为 localStorage 中的字符串。

Everything is stored as a string in localStorage.

因此，当您执行 localStorage.b - localStorage.a 时，您尝试的是尝试从另一个字符串中减去一个字符串。这就是为什么它不起作用。

So when you do localStorage.b - localStorage.a, what you're attempting is trying to subtract one string from another. Which is why it doesn't work.

这篇关于保存并加载日期localstorage的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！