问题描述

在没有任何框架的情况下使用 Web 组件，实现自定义事件的正确方法是什么?例如，假设我有一个自定义元素 x-pop-out 有一个自定义事件 pop 我希望以下所有操作都能正常工作:

Using Web Components without any framework, what is the proper way to implement a custom event? For example, say I have a custom element x-pop-out that has a custom event of pop I would want all of the following to work:

<x-pop-out onpop="someGlobal.doSomething()"/>

var el = document.getElementsByTagName('x-pop-out')[0];
el.onpop = ()=> someGlobal.doSomething();
//or
el.addEventListener('pop', ()=> someGlobal.doSomething());

最后一个我知道该怎么做，但是我需要自定义实现属性和每个 getter/setter 吗?另外，eval() 是从属性执行字符串的适当方式吗?

The last one I get how to do, but do I need to custom implement the attribute and a getter / setter for each? Also, is eval() the appropriate way to execute the string from the attribute?

推荐答案

事件监听器 解决方案(第三种)是最简单的，因为您不必定义任何特殊的东西来捕获事件.

The event listener solution (the third one) is the easiest because you don't have to define anything special to catch the event.

事件处理程序解决方案需要制作一个eval()(第一个，来自属性)或显式调用函数(第二个).

The event handler solutions need to make an eval() (first one, from attribute) or to call the fonction explicitely (second one).

如果你不能使用 eval 你可以改为解析属性字符串.

If you can't use eval you can instead parse the attribute string.

customElements.define( 'x-pop-out', class extends HTMLElement {
    connectedCallback() {
        this.innerHTML = `<button id="Btn">pop</button>`

        this.querySelector( 'button' ).onclick = () => {
            this.dispatchEvent( new CustomEvent( 'pop' ) )
            if ( this.onpop )
                this.onpop()
            else
                eval( this.getAttribute( 'onpop' ) )
        }            
    }
} )

XPO.addEventListener( 'pop', () => console.info( 'pop' ) )

<x-pop-out id=XPO onpop="console.log( 'onpop attribute' )"></x-pop-out>
<hr>
<button onclick="XPO.onpop = () => console.log( 'onpop override' )">redefine onpop</button>

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