javascript - webcomponents - 隐藏 window.onclick 上的下拉菜单

Question

在shadowDOM中创建下拉菜单

近乎完美， 但问题是当单击窗口中的任何其他位置时如何隐藏下拉菜单

class NavComponent extends HTMLElement {
    constructor() {
        super();

        let template = document.currentScript.ownerDocument.querySelector('template');
        let clone = document.importNode(template.content, true);
        let root = this.attachShadow({ mode: 'open' });
        root.appendChild(clone);
    }


    connectedCallback() {
        let ddc = this.shadowRoot.querySelectorAll('.dropdowncontainer')
        let dd = this.shadowRoot.querySelectorAll('.dropdown');
        let ddc_length = ddc.length

        for (let index = 0; index < ddc_length; index++) {
            ddc[index].addEventListener('click', e => {
                dd[index].classList.toggle('show');
            });
        }

        /**   have to update the code ............ */
        window.onclick = function (event) {

        }  /**  END - have to update the code ............ */

    }
}

customElements.define('app-nav', NavComponent)

请引用此demo完整代码

Answer 1

正如 @guitarino 建议的那样，最好的解决方案是定义一个下拉菜单自定义元素。

单击菜单时，调用(第一个)事件处理程序来显示/隐藏菜单，并添加/删除(第二个)dropdown window 上的事件处理程序.

轮到(第二个)dropdown仅当操作位于自定义元素本身之外时，事件处理程序才会调用第一个事件处理程序。

connectedCallback()
{        
    //mousedown anywhere
    this.mouse_down = ev => !this.contains( ev.target ) && toggle_menu()

    //toggle menu and window listener 
    var toggle_menu = () => 
    {
        if ( this.classList.toggle( 'show' ) )
            window.addEventListener( 'mousedown', this.mouse_down )
        else
            window.removeEventListener( 'mousedown', this.mouse_down )
    }

    //click on menu
    this.addEventListener( 'click', toggle_menu )   
}

无论有没有 Shadow DOM，它都可以工作:

customElements.define( 'drop-menu', class extends HTMLElement 
{
  constructor ()
  {
    super()
    this.attachShadow( { mode: 'open'} )
        .innerHTML = '<slot></slot>'
  }

  connectedCallback()
  {        
    //mousedown anywhere
    this.mouse_down = ev => !this.contains( ev.target ) && toggle_menu()
        
    //toggle menu and window listener 
    var toggle_menu = () => 
    {
      if ( this.classList.toggle( 'show' ) )
        window.addEventListener( 'mousedown', this.mouse_down )
      else
        window.removeEventListener( 'mousedown', this.mouse_down )
    }

    //click on menu
    this.addEventListener( 'click', toggle_menu )   
  }

  disconnectedCallback ()
  {
    this.removeEventListener( 'mousedown', this.mouse_down )
  }
} )

drop-menu  {
    position: relative ;
    cursor: pointer ;
    display: inline-block ;
}

drop-menu > output {
    border: 1px solid #ccc ;
    padding: 2px 5px ;
}

drop-menu > ul {
    box-sizing: content-box ;
    position: absolute ;
    top: 2px ; left: 5px ;
    width: 200px;
    list-style: none ;
    border: 1px solid #ccc ;
    padding: 0 ;
    opacity: 0 ;
    transition: all 0.2s ease-in-out ;
    background: white ;
    visibility: hidden ;
    z-index: 2 ;

}

drop-menu.show  > ul {
    opacity: 1 ;
    visibility: visible ;
}

drop-menu > ul > li {
    overflow: hidden ;
    transition: font 0.2s ease-in-out ;
    padding: 2px 5px ;
    background-color: #e7e7e7;
}

drop-menu:hover {
    cursor: pointer;
    background-color: #f2f2f2;
}

drop-menu  ul li:hover {
    background-color: #e0e0e0;
}

drop-menu ul li span {
    float: right;
    color: #f9f9f9;
    background-color: #f03861;
    padding: 2px 5px;
    border-radius: 3px;
    text-align: center;
    font-size: .8rem;
}

drop-menu ul li:hover span {
    background-color: #ee204e;
}

<drop-menu><output>Services</output>
  <ul>
    <li>Graphic desing</li>
    <li>web design</li>
    <li>app design</li>
    <li>theme</li>
  </ul>
</drop-menu>
<drop-menu><output>tutorial</output>
  <ul>
    <li>css <span>12 available</span></li>
    <li>php <span>10 available</span></li>
    <li>javascript <span>40 available</span></li>
    <li>html <span>20 available</span></li>
  </ul>
</drop-menu>