使用 web component 构建一个通用无依赖 html 单文件 select 组件

效果

体验
web component select

web components polyfill 兼容旧版本浏览器的支持插件
https://www.webcomponents.org...

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Web Component 是一系列 web 平台的 API，它们可以允许你创建全新可定制、可重用并且封装的 HTML 标签

定制的组件基于 Web Component 标准构建，可以在现在浏览器上使用，也可以和任意与 HTML 交互的 JavaScript 库和框架配合使用。

它赋予了仅仅使用纯粹的JS/HTML/CSS就可以创建可重用组件的能力。如果 HTML 不能满足需求，我们可以创建一个可以满足需求的 Web Component。

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源码

(function () {
  const selectListDemo = [
    {name: 'test1', value: 1},
    {name: 'test2', value: 2},
    {name: 'test3', value: 3}
  ]

  class MidociSelect extends HTMLElement {
    static get observedAttributes() {
      return ['acitve-title', 'active-sub-title']
    }

    constructor() {
      super()
      this.attachShadow({mode: 'open'})
      this.shadowRoot.innerHTML = `
        
        
        

          1
          
            
          
          

            
1
            
2
            
3
            
4
          
        
      `
      this._wrapperDom = null
      this._listDom = null
      this._titleDom = null
      this._list = []
      this._arrowFlip = false
      this._value = null
      this._name = null
    }

    connectedCallback() {
      this._wrapperDom = this.shadowRoot.querySelector('.wrapper')
      this._listDom = this.shadowRoot.querySelector('.list')
      this._titleDom = this.shadowRoot.querySelector('.title')
      this.initEvent()
      this.list = selectListDemo
    }

    disconnectedCallback() {
      this._wrapperDom.removeEventListener('click', this.flipArrow.bind(this))
      this._wrapperDom.removeEventListener('blur', this.blurWrapper.bind(this))

      this.shadowRoot.querySelectorAll('.item')
        .forEach((item, index) => {
          item.removeEventListener('click', this.change.bind(this, index))
        })
    }

    attributeChangedCallback(attr, oldVal, newVal) {
      // const attribute = attr.toLowerCase()
      // if (attribute === 'descriptions') {
      //   console.log(1)
      //   this.render(newVal)
      // }
    }

    set list(list) {
      if (!this.shadowRoot) return
      this._list = list
      this.render(list)
    }

    get list() {
      return this._list
    }

    set value(value) {
      this._value = value
    }

    get value() {
      return this._value
    }
    
    set name(name) {
      this._name = name
    }

    get name() {
      return this._name
    }

    initEvent() {
      this.initArrowEvent()
      this.blurWrapper()
    }

    initArrowEvent() {
      this._wrapperDom.addEventListener('click', this.flipArrow.bind(this))
    }

    initChangeEvent() {
      this.shadowRoot.querySelectorAll('.item')
        .forEach((item, index) => {
          item.addEventListener('click', this.change.bind(this, index))
        })
    }

    change(index) {
      this.changeTitle(this._list, index)

      let changeInfo = {
        detail: {
          value: this._value,
          name: this._name
        },
        bubbles: true
      }
      let changeEvent = new CustomEvent('change', changeInfo)
      this.dispatchEvent(changeEvent)
    }

    changeTitle(list, index) {
      this._value = list[index].value
      this._name = list[index].name
      this._titleDom.innerText = this._name
    }

    flipArrow() {
      if (!this._arrowFlip) {
        this.showList()
      } else {
        this.hideList()
      }
    }

    showList() {
      this._arrowFlip = true
      this._wrapperDom.classList = 'wrapper flip'
    }

    hideList() {
      this._arrowFlip = false
      this._wrapperDom.classList = 'wrapper'
    }

    blurWrapper() {
      this._wrapperDom.addEventListener('blur', (event) => {
        event.stopPropagation()
        this.hideList()
      })
    }

    render(list) {
      if (!list instanceof Array) return
      let listString = ''
      list.forEach((item) => {
        listString += `
          
${item.name}
        `
      })
      this._listDom.innerHTML = listString
      this.changeTitle(list, 0)
      this.initChangeEvent()
    }
  }

  const FrozenMidociSelect = Object.freeze(MidociSelect);
  customElements.define('midoci-select', FrozenMidociSelect);
})()

注意：如果父元素高度太低，需要关闭父元素的 overflow 属性，否则会遮盖 下拉列表

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使用