PureScript 语言 Preact 开发图片懒加载组件 Intersection Observer 封装

PureScript阿木 发布于 3 天前 9 次阅读

使用PureScript和Preact开发图片懒加载组件：Intersection Observer封装实践

随着互联网的快速发展，网页加载速度成为用户体验的重要指标之一。图片懒加载技术可以有效减少初始页面加载时间，提高页面性能。本文将围绕PureScript语言和Preact框架，结合Intersection Observer API，实现一个高效的图片懒加载组件。

PureScript简介

PureScript是一种函数式编程语言，它基于Haskell，旨在提供一种简洁、安全、高效的编程方式。PureScript编译成JavaScript，可以在浏览器和Node.js环境中运行。Preact是一个轻量级的React库，它提供了React的核心功能，但体积更小，性能更高。

Preact简介

Preact是一个简洁的React实现，它提供了React的核心API，如JSX、组件、生命周期等。Preact的体积小，性能高，非常适合用于构建高性能的Web应用。

Intersection Observer API简介

Intersection Observer API是一个现代浏览器API，用于异步观察目标元素与其祖先元素或顶级文档视窗（viewport）交叉状态的变化。它可以用来实现图片懒加载、无限滚动等功能。

图片懒加载组件设计

组件结构

我们的图片懒加载组件将包含以下部分：

1. `LazyImage`：负责渲染图片，并使用Intersection Observer API监听图片是否进入视窗。
2. `observer`：一个封装好的Intersection Observer实例，用于监听图片元素。
3. `loadImage`：一个函数，用于在图片进入视窗时加载图片。

组件实现

下面是使用PureScript和Preact实现图片懒加载组件的代码：

```purescript
module LazyImage where

import Preact
import PreactDOM
import Effect
import Effect.Aff
import Effect.Class (liftEffect)
import Effect.Class.Unsafe (unsafePerformEffect)
import Data.Array (map)
import Data.Maybe (Maybe(Just, Nothing))
import Data.Nullable (toNullable)
import Data.String (Pattern, contains)
import DOM.Event.Event (Event)
import DOM.Event.EventTarget (addEventListener)
import DOM.Node (Node, parentNode, nodeType, nodeValue, setAttribute)
import DOM.Node.NodeType (TEXT_NODE)
import DOM.Node.Text (nodeValue)
import DOM.Node.Element (getElementById, querySelectorAll, setAttributeNS, setAttribute)
import DOM.HTML (window)
import DOM.HTML.Window (document)
import DOM.HTML.Element (getElementById)
import DOM.HTML.HTMLElement (innerHTML, style)
import DOM.HTML.HTMLElement (style)
import DOM.HTML.HTMLElement (style)
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