2023年了该了解下WebComponent使用教程
正文WebComponent 是官方定义的自定义组件实现方式,它可以让开发者不依赖任何第三方框架(如Vue,React)来实现自定义页面组件;达到组件复用效果
一个简单例子,让页面显示 hello world:
<body>
<!-- 使用组件的方式 -->
<my-text />
<script>
class MyText extends HTMLElement {
constructor() {
super();
this.append("hello world");
}
}
window.customElements.define("my-text", MyText);
</script>
</body>
三项主要技术
1、Custom elements (自定义元素)
[*]一组 JavaScript API,允许您定义 custom elements 及其行为,然后可以在您的用户界面中按照需要使用它们
分为两种形式:
自主定制元素:是独立的元素,它不继承其他内建的 HTML 元素,可以直接把它们写成 HTML 标签的形式,来在页面上使用,例如我们刚才自定义的 <my-text>
自定义内置元素:继承自内置的 HTML 元素。指定所需扩展的元素
[*]使用时需通过 is 属性指定 custom element 的名称,必须包含一个短横线
[*]注册的时候必须使用 extends 的属性
<!-- 自定义内置元素 使用 is-->
<body>
<!-- 使用组件的方式 -->
<p is="color-p" color="green">云牧</p>
<script>
class ColorP extends HTMLParagraphElement {
constructor() {
super();
this.style.color = this.getAttribute("color");
}
}
window.customElements.define("color-p", ColorP, { extends: "p" });
</script>
</body>推荐在 connectedCallback 生命周期函数,处理节点操作
<!-- 自主定制元素-->
<body>
<my-text />
<script>
class MyText extends HTMLElement {
constructor() {
super();
}
connectedCallback() {
this.append("hello world");
}
}
window.customElements.define("my-text", MyText);
</script>
</body>
生命周期函数
connectedCallback:插入文档时,可能被多次触发,比如删除后又添加到文档
disconnectedCallback:从文档删除时,可配置做清理工作
adoptedCallback:被移动新文档时
attributeChangedCallback:属性变化时
[*]配合 observedAttributess 属性一起使用,指定监听的属性
[*]使用 setAttribute 方法更新属性
不同操作触发的生命周期函数:
https://img.jbzj.com/file_images/article/202302/20230224083030029.png
例子:
<body>
<div id="container">
<p is="my-text" text="云牧" id="myText"></p>
</div>
<button id="btnUpdateText">更新属性</button>
<button id="btnRemove">删除节点</button>
<button id="btnRestore">恢复节点</button>
<button id="btnAdopt">移动节点</button>
<iframe src="./ifr.html" id="ifr"></iframe>
<script>
class MyText extends HTMLParagraphElement {
constructor() {
super();
}
connectedCallback() {
console.log("生命周期:connectedCallback");
this.append("你好:" + this.getAttribute("text"));
}
disconnectedCallback() {
console.log("生命周期:disconnectedCallback");
this.innerHTML = "";
}
// 监测的属性
static get observedAttributes() {
return ["text"];
}
attributeChangedCallback(name, oldValue, newValue) {
console.log("生命周期:attributeChangedCallback", name, oldValue, newValue);
// 最先触发是此函数,判断是不是第一次触发,第一次的话,只由 connectedCallback 处理
if (oldValue != null) {
this.replaceChildren("你好:" + newValue);
}
}
adoptedCallback() {
console.log("生命周期:adoptedCallback");
}
}
window.customElements.define("my-text", MyText, { extends: "p" });
const myText = document.getElementById("myText");
btnUpdateText.addEventListener("click", function (e) {
myText.setAttribute("text", "黛玉");
});
btnRemove.addEventListener("click", function (e) {
myText.remove();
});
btnRestore.addEventListener("click", function (e) {
container.appendChild(myText);
});
btnAdopt.addEventListener("click", () => {
const textNode = ifr.contentWindow.document.getElementById("myText");
container.appendChild(document.adoptNode(textNode));
});
</script>
</body>
2、HTML templates(HTML 模板)
[*]使用 JS 模板字串符的方式创建模板,提示不友好,复用性差
<body>
<product-item
name="关东煮"
img="//img10.360buyimg.com/seckillcms/s200x200_jfs/t1/121953/18/20515/175357/61e7dc79Ee0acbf20/4f4f56abd2ea2f75.jpg!cc_200x200.webp"
price="49.8"
></product-item>
<script>
class ProductItem extends HTMLElement {
constructor() {
super();
}
connectedCallback() {
const content = `
<img class="img" src="https://misc.360buyimg.com/lib/skin/e/i/error-jd.gif" />
<div class="name"></div>
<div class="price"></div>
`;
this.innerHTML = content;
this.querySelector(".img").src = this.getAttribute("img");
this.querySelector(".name").innerText = this.getAttribute("name");
this.querySelector(".price").innerText = this.getAttribute("price");
}
}
window.customElements.define("product-item", ProductItem);
</script>
</body>template 方式
<body>
<!-- template -->
<template id="tpl-product-item">
<img class="img" src="https://misc.360buyimg.com/lib/skin/e/i/error-jd.gif" />
<div class="name"></div>
<div class="price"></div>
</template>
<product-item
name="关东煮"
img="//img10.360buyimg.com/seckillcms/s200x200_jfs/t1/121953/18/20515/175357/61e7dc79Ee0acbf20/4f4f56abd2ea2f75.jpg!cc_200x200.webp"
price="49.8"
></product-item>
<script>
class ProductItem extends HTMLElement {
constructor() {
super();
}
connectedCallback() {
const content = document.getElementById("tpl-product-item").content.cloneNode(true);
// 插入克隆的模板内容
this.append(content);
this.querySelector(".img").src = this.getAttribute("img");
this.querySelector(".name").innerText = this.getAttribute("name");
this.querySelector(".price").innerText = this.getAttribute("price");
}
}
window.customElements.define("product-item", ProductItem);
</script>
</body>slot
<body>
<template id="tpl-test">
<style>
.title {
color: green;
}
</style>
<div class="title">标题</div>
<slot name="slot-des">默认内容</slot>
</template>
<test-item>
<div slot="slot-des">不是默认内容</div>
</test-item>
<script>
class TestItem extends HTMLElement {
constructor() {
super();
}
connectedCallback() {
const content = document.getElementById("tpl-test").content.cloneNode(true);
const shadow = this.attachShadow({ mode: "open" });
shadow.append(content);
}
}
window.customElements.define("test-item", TestItem);
</script>
</body>
3、Shadow DOM(影子 DOM)
https://img.jbzj.com/file_images/article/202302/20230224083030030.png
影子DOM,其内部样式不共享
<body>
<!--不受外部 .container.container 的颜色影响 -->
<my-item-s></my-item-s>
<div class="container">My item</div>
<style>
.container.container {
color: green;
}
</style>
<template id="tpl">
<style>
.container {
color: pink;
}
</style>
<div class="container">My Item</div>
</template>
<script>
class MyItemShadow extends HTMLElement {
constructor() {
super();
}
connectedCallback() {
const content = document.getElementById("tpl").content.cloneNode(true);
const shadow = this.attachShadow({ mode: "open" });
shadow.append(content);
}
}
window.customElements.define("my-item-s", MyItemShadow);
</script>
</body>影子DOM,其内部元素不可以直接被访问到
有一个重要的参数 mode
[*]open: shadow root 元素通过 js 从外部访问根节点
[*]closed:拒绝 js 从外部访问关闭的 shadow root 节点
<body>
<template id="tpl">
<div class="title"></div>
<div class="des"></div>
</template>
<note-item class="note-item" title="标题" des="内容"></note-item>
<script>
class NoteItem extends HTMLElement {
constructor() {
super();
}
connectedCallback() {
const content = document.getElementById("tpl").content.cloneNode(true);
const shadow = this.attachShadow({ mode: "open" });
shadow.append(content);
// 如果是 open 则可以继续访问操作内部 dom
// console.log(document.querySelector(".note-item").shadowRoot.querySelector(".title"));
shadow.querySelector(".title").textContent = this.getAttribute("title");
shadow.querySelector(".des").textContent = this.getAttribute("des");
}
}
window.customElements.define("note-item", NoteItem);
</script>
</body>引入外部样式:
<body>
<template id="tpl">
<!-- 方式一: -->
<link rel="stylesheet" href="index.css" rel="external nofollow"/>
<div>My Item</div>
</template>
<my-item></my-item>
<script>
class MyItem extends HTMLElement {
constructor() {
super();
}
connectedCallback() {
const content = document.getElementById("tpl").content.cloneNode(true);
const shadow = this.attachShadow({ mode: "open" });
shadow.append(content);
// 方式二:
const linkEl = document.createElement("link");
linkEl.setAttribute("rel", "stylesheet");
linkEl.setAttribute("href", "index.css");
shadow.appendChild(linkEl);
}
}
window.customElements.define("my-item", MyItem);
</script>
</body>
动态创建 webComponent 组件例子
[*]通过创建 商品 组件,并使得点击能跳转
<body>
<div id="product-list" style="display: flex"></div>
<template id="product-item">
<style>
.product-item {
margin-left: 15px;
cursor: pointer;
}
.img {
width: 100px;
}
.name {
text-align: center;
}
.price {
color: #999;
text-align: center;
}
</style>
<div class="product-item">
<img class="img" src="https://misc.360buyimg.com/lib/skin/e/i/error-jd.gif" />
<div class="name"></div>
<div class="price"></div>
</div>
</template>
<script>
class ProductItemElement extends HTMLElement {
constructor(props) {
super(props);
this.addEventListener("click", () => {
window.open(`https://item.jd.com/${this.id}.html`);
});
}
connectedCallback() {
const shadow = this.attachShadow({ mode: "open" });
const content = document.getElementById("product-item").content.cloneNode(true);
content.querySelector(".img").src = this.img;
content.querySelector(".name").innerText = this.name;
content.querySelector(".price").innerText = this.price;
shadow.appendChild(content);
}
}
window.customElements.define("product-item", ProductItemElement);
</script>
<script>
const products = [
{
name: "关东煮",
img: "//img10.360buyimg.com/seckillcms/s200x200_jfs/t1/121953/18/20515/175357/61e7dc79Ee0acbf20/4f4f56abd2ea2f75.jpg!cc_200x200.webp",
id: "10026249568453",
price: 49.8
},
{
name: "土鸡蛋",
img: "//img11.360buyimg.com/seckillcms/s200x200_jfs/t1/172777/32/27438/130981/61fbd2e0E236000e0/7f5284367e2f5da6.jpg!cc_200x200.webp",
id: "10024773802639",
price: 49.8
},
{
name: "东北蜜枣粽子",
img: "//img20.360buyimg.com/seckillcms/s200x200_jfs/t1/129546/31/19459/110768/60b1f4b4Efd47366c/3a5b80c5193bc6ce.jpg!cc_200x200.webp",
id: "10035808728318",
price: 15
}
];
const productList = document.getElementById("product-list");
const elList = products.map(product => {
// 创建组件
const el = document.createElement("product-item");
el.img = product.img;
el.name = product.name;
el.price = product.price;
el.id = product.id;
return el;
});
productList.append.apply(productList, elList);
</script>
</body>以上就是2023年了该了解下WebComponent使用教程的详细内容,更多关于WebComponent使用教程的资料请关注脚本之家其它相关文章!
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