Vanilla Web Component自定义事件属性和属性

问题描述

在没有任何框架的情况下使用Web Components，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 ，其自定义事件为 pop 我想要以下所有工作：

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());

我得到的最后一个怎么做，但我是否需要自定义实现属性和getter / setter每个？另外，是 eval（）从属性执行字符串的适当方法吗？

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（第三个）是最简单的，因为您不必定义任何特殊的事件来捕获事件。

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创建一个 eval（）（第一个，来自属性）或明确调用该函数（第二个）一个）。

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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