vue中4个自定义指令讲解及实例用法

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 += 'top:' + moveY + 'px;left:' + moveX + 'px;'      }      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=='TEXTAREA' || arr[i].tagName=='INPUT'){          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,'**').length +'/'+value//eslint-disable-line    })  },  update(el,binding){    console.log('update');    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=='TEXTAREA' || arr[i].tagName=='INPUT'){          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,'**').length +'/'+value//eslint-disable-line    })  },  inserted(el,binding){    console.log('inserted');    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=='TEXTAREA' || arr[i].tagName=='INPUT'){        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('div')    if(el.children[current].tagName=='TEXTAREA'){//是textarea，定位在右下角      div.style = 'color:#909399;position:absolute;font-size:12px;bottom:5px;right:10px;'    }else{      let styStr = ''      if(!el.classList.contains('is-disabled')){//input框不是置灰的状态则添加背景颜色        styStr = 'background:#fff;'      }      div.style = 'color:#909399;position:absolute;font-size:12px;bottom:2px;right:10px;line-height:28px;height:28px;'+styStr    }     div.innerHTML = '0/'+ value    el.appendChild(div)    el.children[current].style.paddingRight = '60px'     el.oninput = () =>{      let val = el.children[current].value      val = val.replace(/[^/x00-/xff]/g,'**') //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 + '/' + 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,'**').length +'/'+value//eslint-disable-line       }    }   },})

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

Vue.directive('anchor',{  inserted(el,binding){    let { value } = binding    let timer = null    el.addEventListener('click',function(){      // 当前元素距离可视区域顶部的距离      let currentTop = el.getBoundingClientRect().top      animateScroll(currentTop)    },false)         function animateScroll(currentTop){      if(timer){        clearInterval(timer)      }      let c = 9      timer = setInterval(() =>{        if(c==0){          clearInterval(timer)        }        c--        window.scrollBy(0,(currentTop-value)/10)      },16.7)    }   }})

<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']"`)    }  }})