Vue で知っておく価値のある 4 つのカスタム命令 (実践的な共有)

Vue.directive('drag', {
  inserted(el) {
    let header = el.querySelector('.dialog_header')
    header.style.cssText += ';cursor:move;'
    header.onmousedown = function (e) {
      //获取当前可视区域宽、高
      let clientWidth = document.documentElement.clientWidth
      let clientHeight = document.documentElement.clientHeight

      //获取自身宽高
      let elWidth = el.getBoundingClientRect().width
      let elHeight = el.getBoundingClientRect().height

      //获取当前距离可视区域的top、left
      let elTop = el.getBoundingClientRect().top
      let elLeft = el.getBoundingClientRect().left

      //获取点击时候的坐标
      let startX = e.pageX
      let startY = e.pageY

      document.onmousemove = function (e) {
        //元素偏移量 = 鼠标滑动后的坐标 - 鼠标初始点击元素时的坐标 + 初始点击时元素距离可视区域的top、left
        let moveX = e.pageX - startX + elLeft
        let moveY = e.pageY - startY + elTop

        //将可视区域作为边界，限制在可视区域里面拖拽
        if ((moveX + elWidth) > clientWidth || moveX < 0 || (moveY + elHeight) > clientHeight || moveY < 0) {
          return
        }

        el.style.cssText += &#39;top:&#39; + moveY + &#39;px;left:&#39; + moveX + &#39;px;&#39;
      }
      document.onmouseup = function () {
        document.onmousemove = null
        document.onmouseup = null
      }
    }
  }
})

Vue.directive('wordlimit',{
  bind(el,binding){
    console.log('bind');
    let { value } = binding
    Vue.nextTick(() =>{
      //找到输入框是textarea框还是input框
      let current = 0
      let arr = Array.prototype.slice.call(el.children)
      for (let i = 0; i < arr.length; i++) {
        if(arr[i].tagName==&#39;TEXTAREA&#39; || arr[i].tagName==&#39;INPUT&#39;){
          current = i
        }
      }
  
      //更新当前输入框的字节数
      el.children[el.children.length-1].innerHTML = el.children[current].value.replace(/[^\x00-\xff]/g,&#39;**&#39;).length +&#39;/&#39;+value//eslint-disable-line
    })
  },
  update(el,binding){
    console.log(&#39;update&#39;);
    let { value } = binding
    Vue.nextTick(() =>{
      //找到输入框是textarea框还是input框
      let current = 0
      let arr = Array.prototype.slice.call(el.children)
      for (let i = 0; i < arr.length; i++) {
        if(arr[i].tagName==&#39;TEXTAREA&#39; || arr[i].tagName==&#39;INPUT&#39;){
          current = i
        }
      }
  
      //更新当前输入框的字节数
      el.children[el.children.length-1].innerHTML = el.children[current].value.replace(/[^\x00-\xff]/g,&#39;**&#39;).length +&#39;/&#39;+value//eslint-disable-line
    })
  },
  inserted(el,binding){
    console.log(&#39;inserted&#39;);
    let { value } = binding

    //找到输入框是textarea框还是input框
    let current = 0
    let arr = Array.prototype.slice.call(el.children)
    for (let i = 0; i < arr.length; i++) {
      if(arr[i].tagName==&#39;TEXTAREA&#39; || arr[i].tagName==&#39;INPUT&#39;){
        current = i
      }
    }

    //创建包裹字数限制的元素，并定位布局在textarea和input框上
    let div = document.createElement(&#39;div&#39;)
    if(el.children[current].tagName==&#39;TEXTAREA&#39;){//是textarea，定位在右下角
      div.style = &#39;color:#909399;position:absolute;font-size:12px;bottom:5px;right:10px;&#39;
    }else{
      let styStr = &#39;&#39;
      if(!el.classList.contains(&#39;is-disabled&#39;)){//input框不是置灰的状态则添加背景颜色
        styStr = &#39;background:#fff;&#39;
      }
      div.style = &#39;color:#909399;position:absolute;font-size:12px;bottom:2px;right:10px;line-height:28px;height:28px;&#39;+styStr
    }

    div.innerHTML = &#39;0/&#39;+ value
    el.appendChild(div)
    el.children[current].style.paddingRight = &#39;60px&#39;

    el.oninput = () =>{
      let val = el.children[current].value
      val = val.replace(/[^\x00-\xff]/g,&#39;**&#39;) //eslint-disable-line
      // 字数限制的盒子插入到el后是最后一个元素
      el.children[el.children.length-1].innerHTML = val.length + &#39;/&#39; + value
      if(val.length>value){
        let cnLen = 0 //一个字节的字数
        let enLen = 0 //两个字节的字数

        if(val.match(/[^**]/g) && val.match(/[^**]/g).length){
          enLen = val.match(/[^**]/g).length // 计算一个字节的字数

          //一个字节两个字节都有的情况
          if((value - val.match(/[^**]/g).length)>0){
            cnLen = Math.floor((value - val.match(/[^**]/g).length)/2)
          }else{
            cnLen = 0
          }
        }else{ //全部两个字节的情况
          enLen = 0
          cnLen = Math.floor(value/2)
        }

        if(enLen>value){
          enLen = value
        }

        //超过限定字节数则截取
        el.children[current].value = el.children[current].value.substr(0,enLen+cnLen)

        //更新当前输入框的字节数
        el.children[el.children.length-1].innerHTML = el.children[current].value.replace(/[^\x00-\xff]/g,&#39;**&#39;).length +&#39;/&#39;+value//eslint-disable-line

      }
    }

  },
})

<el-input type="textarea" rows="3" v-wordlimit="20" v-model="value"></el-input>

<div class="box" v-anchor="20" style="color:red;">是的</div>

Vue.directive('hasRole',{
  inserted(el,binding){
    let { value } = binding
    let roles = JSON.parse(sessionStorage.getItem('userInfo')).roleIds

    if(value && value instanceof Array && value.length>0){

      let hasPermission = value.includes(roles)

      if(!hasPermission){
        el.parentNode && el.parentNode.removeChild(el)
      }
    }else{
      throw new Error(`请检查指令绑定的表达式，正确格式例如 v-hasRole="['admin','reviewer']"`)
    }
  }
})