localStorage 和布尔“字符串"

localStorage and boolean #39;string#39;(localStorage 和布尔“字符串)

问题描述

在localStorage中存储布尔值，这个值被转换为字符串.现在尝试将此值从 localStorage 转换回布尔值，我需要使用 JSON.parse() 方法，更方便的 !! 不起作用.

Storing boolean value in localStorage, this value is converted to string. Now trying to converting back this value from localStorage to boolean, i need to use JSON.parse() method, the more handy !! doesn't work.

代码示例:

var test = false;
localStorage['test'] = test;
console.log("JSON.parse returns: ", JSON.parse(localStorage['test']), "expected: ", test);
console.log("'!!' returns: ", !! localStorage['test'], "expected: ", test);

-jsFiddle-

我很困惑为什么会出现这种行为.有什么解释吗?

I'm quite confused why this behaviour. Any explaination?

PS:在这里使用 getter/setter localStorage 方法无关紧要，结果相同.

PS: using getter/setter localStorage methods doesn't matter here, same result.

推荐答案

本地存储存储字符串，恐怕不管输入是什么(如果你用一个对象喂它，它会自动转换成它的标准toString() 方法)...所以你在做 !!在字符串上测试，它总是true.

Local storage stores strings , I'm afraid, whatever the input (if you feed it with an object, it will be converted automatically with its standard toString() method)... So you're doing !! test on a string, which is always true.

在处理 DOM 存储

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