使用动态扩展 class 表达式创建新元素

Question

是否可以传递一个class表达式作为参数？

还没有尝试过 eval 路线..

// CardtsElements.Zone contains a valid class expression
// used to create a valid Zone Custom Element
let extend = (source, name, definitionClassExpression) => 
    customElements.define('CARDTS-' + name, 
                           class extends CardtsElements[source] definitionClassExpression);
                                                              ^^^^SYNTAX ERROR^^^^^^^^^^

// Create a new 'CARDTS-FOUNDATION' element extending 'CARDTS-ZONE'
extend('Zone','Foundation', {
    static get observedAttributes() {
        return ['suit','draggable','drop'];
    }
    constructor(){}
});

Answer 1

您可以将 class 表达式 作为 class 工厂 函数传递：

a（箭头）function、
带一个参数（superclass）：你要扩展的class，
这将 return 新派生的 class。

// CardtsElements.Zone contains a valid class expression
// used to create a valid Zone Custom Element
var CardtsElements = {
  'Zone': class extends HTMLElement {
      constructor() { super() ; console.log('zone element created') }
      connectedCallback(){ console.log('connected Zone')}
      zone() { console.log( 'zone' ) }
  }
}

let extend = (source, name, classFactory) => 
    customElements.define('cardts-' + name, classFactory(CardtsElements[source])) 


// Create a new 'CARDTS-FOUNDATION' element extending 'CARDTS-ZONE'
extend('Zone','foundation', superclass => 
     class extends superclass {
         constructor() { super() ; console.log(this.localName + ' created') }
         static get observedAttributes() { return ['suit','draggable','drop'] }
         connectedCallback(){ 
            super.connectedCallback();
            console.log('connected',this.localName)
         }
         foundation() { console.log('foundation') }
     }
)

CF.zone()
CF.foundation()

<cardts-foundation id=CF>Cardts Foundation</cardts-foundation>

使用动态扩展 class 表达式创建新元素

Creating new element with a dynamic extends class expression

javascript

class

web-component

ecmascript-6

custom-element