如果localStorage键值不存在 [英] if localStorage key value doesn't exist

问题描述

如果没有localStorage键值，我正在尝试隐藏div.

I am trying to hide my div if there is no a localStorage key value.

在下面的代码行中，我仅实现了在localStorage键完全删除时隐藏div，但是如果localStorage 键根本没有任何价值，则需要执行同样的操作.

With the line below I achieved only to hide a div when localStorage key completely deleted but need to do the same if localStorage key hasn't got any value at all just [].

 window.localStorage.getItem('items') === null

它将如何执行?

推荐答案

您可以使用OR运算符||

var items = window.localStorage.getItem('items')

if (items === null || items.length === 0)
{
    // items is null, [] or '' (empty string)
}

如果您还必须在某处检查undefined，则可以将=== null更改为== null或使用类似这样的额外条件进行扩展

If you have to check for undefined somewhere as well you can change === null to == null or expand with an extra condition like this

if (items === undefined || items === null || items.length === 0)
{
    // items is undefined, null, [] or '' (empty string)
}

编辑:这是您可以直接获取数组的方法

Here is what you can do to get the array directly

var items = JSON.parse(window.localStorage.getItem('items'))

if (items === null || items.length === 0)
{
    // items is null or []
}

这篇关于如果localStorage键值不存在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！