Vue的v-for中列表项拖拽排序详细方法

首先：HTML中，关键点是监听拖拽的三个阶段，即：dragstart/dragover/dragend，注意：要拖拽元素必须加上draggable="true"

<ul @dragstart="onDragStart"
    @dragover="onDragOver"
    @dragend="onDragEnd"
    ref="taskListUl">
  <li v-for="(subTask,index) in subTaskList"
      draggable="true"
      :id="subTask.id"
      :key="subTask.id">
    <el-row>
      <el-col :lg="20">
        <div  class="main">
          <el-row>
            <el-col :span="3"><el-checkbox></el-checkbox></el-col>
            <el-col :span="21" class="taskEdit" v-if="show.isShowEdit !== index" :title="subTask.name">{{subTask.name}}</el-col>
            <el-col :span="21" v-else>
              <el-row style=" 300px;">
                <el-form ref="taskEditForm" :model="subTask">
                  <el-col :span="14">
                    <el-input v-model="subTask.name" size="mini"
                              @keyup.enter.native="saveSubTask('subTaskForm',subTask);showEditTitle()"></el-input>
                  </el-col>
                  <el-col :span="10">
                    <el-button type="primary" style="font-size:12px;color:#fff;margin-left:4px;padding:5px 8px;border:0;"
                               size="mini" @click="saveSubTask('subTaskForm',subTask);handleTaskEdit()">保存</el-button>
                    <el-button style="font-size:12px;padding:5px 8px;border:0;" size="mini" @click="handleTaskEdit">取消</el-button>
                  </el-col>
                </el-form>
              </el-row>
            </el-col>
          </el-row>
        </div>
        <div class="icon1" v-if="show.isShowEdit !== index">
          <el-button circle size="mini" @click="handleTaskEdit(index)"><i class="el-icon-edit"></i></el-button>
          <el-button circle size="mini" @click="handleTaskDelete(index,subTask.id)"><i class="el-icon-delete"></i></el-button>
        </div>
        <div class="icon2">
          <el-button circle size="mini"><i class="el-icon-s-finance"></i></el-button>
          <el-button circle size="mini"><i class="el-icon-user"></i></el-button>
        </div>
      </el-col>
    </el-row>
  </li>
</ul>
其次，JavaScript中
data() {
  return {
  　　subTaskList: []

　　}
},
methods: {

onDragStart(event){     //用于在拖拽开始时获取被拖拽元素
  console.log("drag start")
  this.draging=event.target;
  console.log(this.draging);
},
onDragOver(event){    //用于在拖拽过程中，获取拖拽元素经过的对象，以及对元素顺序做出调整
  console.log('drag move');
  this.target=event.path[5];    //li的位置
  let targetTop=event.target.getBoundingClientRect().top;
  let dragingTop=this.draging.getBoundingClientRect().top;
  if (this.target.nodeName === "LI"&&this.target !== this.draging) {
    if (this.target) {
      if (this.target.animated) {
        return;
      }
    }
    if(this._index(this.draging)<this._index(this.target)){
      this.target.parentNode.insertBefore(this.draging,this.target.nextSibling);
    }else{
      this.target.parentNode.insertBefore(this.draging, this.target);
    }
    this._anim(targetTop,this.target);
    this._anim(dragingTop,this.draging);
  }
},
_anim(startPos,dom) {    //用于重绘元素
  let offset = startPos - dom.getBoundingClientRect().top;
  dom.style.transition = "none";
  dom.style.transform = `translateY(${offset}px)`;
  //触发重绘
  dom.offsetWidth;
  dom.style.transition="transform .3s";
  dom.style.transform=``;
  clearTimeout(dom.animated);
  dom.animated=setTimeout(()=>{
    dom.style.transition="";
    dom.style.transform=``;
    dom.animated=false;
  },300)
},
onDragEnd(event){   //结束后跟俊最终拖拽调整subTaskList数组

  console.log('drag end');
  //获取排序后的li节点数组
  let currentNodes=Array.from(this.$refs.taskListUl.childNodes);
  let newArr = [];
  for(let i=0;i<currentNodes.length;i++) {
    for(let j=0;j<this.subTaskList.length;j++) {
      if(currentNodes[i].id == this.subTaskList[j].id){
        newArr[i] = this.subTaskList[j];
      }
    }
  }
  this.subTaskList = newArr;
  console.log(this.subTaskList);
},

_index(el){    //用于根据元素id来获取对应元素的索引值

  let domData=Array.from(this.$refs.taskListUl.childNodes);
  return domData.findIndex((currentValue,index,arr)=>{
    return el.id == currentValue.id;
  });
},

}