elementUI树形组件添加连线和自定义图标

1.elementUI的树形组件官网样例节点之间是没有连线的，想要实现如下图节点之间出现连线需要自己定义树形插件的样式覆盖el-tree内部的样式类

首先要给el-tree添加两个样式类
 

 一个添加到el-tree本身的class上，另外一个添加到包裹el-tree的外层div,具体的样式代码如下

/* 树形结构节点添加连线 */
.tree /deep/ .el-tree-node {
  position: relative;
  padding-left: 16px;
}

.tree /deep/ .el-tree-node__children {
  padding-left: 16px;
}

.tree /deep/ .el-tree-node :last-child:before {
  height: 38px;
}

.tree /deep/ .el-tree > .el-tree-node:before {
  border-left: none;
}

.tree-container /deep/ .el-tree > .el-tree-node:after {
  border-top: none;
}

.tree /deep/ .el-tree-node:before {
  content: "";
  left: -4px;
  position: absolute;
  right: auto;
  border-width: 1px;
}

.tree /deep/ .el-tree-node:after {
  content: "";
  left: -4px;
  position: absolute;
  right: auto;
  border-width: 1px;
}
.tree /deep/ .el-tree-node__expand-icon.is-leaf {
  display: none;
}

.tree /deep/ .el-tree-node:before {
  border-left: 1px dashed #b8b9bb;
  bottom: 0px;
  height: 100%;
  top: -26px;
  width: 1px;
}

.tree /deep/ .el-tree-node:after {
  border-top: 1px dashed #b8b9bb;
  height: 20px;
  top: 12px;
  width: 24px;
}

这样就可以实现各个节点之间的连线，自己也可以自定义连线的颜色线条粗细等一系列属性 

2.节点前添加自定义图标

使用官方提供的scoped slot插槽

 将需要的图标样式类存储在icon字段中，后台向前台返回数据时取出绑定到class样式即可显示出图标