阿木博主一句话概括：基于PureScript和Preact的购物车跨页面状态持久化实现与localStorage应用
阿木博主为你简单介绍：
随着Web应用的日益复杂，用户在浏览过程中可能会在不同的页面间切换，这就要求应用能够保持用户的状态，如购物车中的商品信息。本文将探讨如何使用PureScript语言和Preact框架结合localStorage实现购物车的跨页面状态持久化。
关键词：PureScript，Preact，localStorage，购物车，状态持久化
一、
在Web应用中，购物车是一个常见的功能，它允许用户在浏览商品时添加商品到购物车，并在最后进行结算。为了提升用户体验，购物车中的商品信息需要在用户切换页面时保持不变。localStorage作为一种简单的客户端存储机制，可以很好地实现这一功能。本文将介绍如何使用PureScript语言和Preact框架结合localStorage实现购物车的跨页面状态持久化。
二、技术选型
1. PureScript：PureScript是一种函数式编程语言，它基于Haskell，旨在提供一种简洁、类型安全的编程方式。PureScript与JavaScript有着良好的兼容性，可以无缝地与现有的JavaScript代码库集成。
2. Preact：Preact是一个轻量级的React替代品，它提供了与React相似的开发体验，但体积更小，性能更高。Preact非常适合构建需要高性能和轻量级框架的应用。
3. localStorage：localStorage是Web Storage API的一部分，它允许Web应用在用户的浏览器中存储键值对。localStorage的数据存储在用户的本地计算机上，即使关闭浏览器也不会丢失。
三、实现步骤
1. 创建Preact应用
我们需要创建一个Preact应用。以下是创建Preact应用的示例代码：
purescript
import Preact as P
import PreactDOM as PDOM
type Props = {}
type State =
{ items :: Array String }
initialState :: State
initialState = { items: [] }
App :: ReactComponent Props State
App =
P.component
{ render: render
, initialState: initialState
}
where
render :: Props -> State -> P.Element
render _ state =
P.div_
[ P.h1_ [ P.text "购物车" ]
, P.div_
[ P.button
{ onClick: _ -> addItem "商品1" }
[ P.text "添加商品1" ]
, P.button
{ onClick: _ -> addItem "商品2" }
[ P.text "添加商品2" ]
]
, P.div_
[ P.text "购物车中的商品：" ]
, P.div_
[ P.ul_
(map (item -> P.li_ [ P.text item ]) state.items)
]
]
addItem :: String -> Effect Unit
addItem item = do
state <- P.getState App
P.setState App { items = state.items [item] }
2. 使用localStorage存储购物车数据
在Preact应用中，我们可以使用localStorage来存储和读取购物车数据。以下是使用localStorage存储和读取购物车数据的示例代码：
```purescript
import Data.Array as Array
import Data.Either as Either
import Data.Maybe as Maybe
import Effect as Effect
import Effect-dom as EffectDOM
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