How does the elementui tree control listen to the expanded state of a node?

< H2 > how does the elementui tree control listen to the expanded state of a node? < / H2 > 
<el-tree 
                :data="treeDatas" 
                :props="defaultProps" 
                :default-expand-all="true" 
                @node-click="handleNodeClick"
                :expand-on-click-node="false"
                :indent = "10"                 
                ref="tree">
                  <span class="custom-tree-node" slot-scope="{ node, treeDatas }">
                    <span :class="handleClass(node.data)"><i :class="node.icon"></i>{{ node.label }}</span>
                  </span>
                </el-tree>
The requirement of the

project is to change the small icon of the current node when the state of the node deployment changes. The icon is the icon component in the elementUI used.
now is stuck in getting the status of the node here, ask all the gods for guidance!

Vue.js
Aug.27,2021
The callback of the

node-click node when clicked consists of three parameters: the object corresponding to the node in the array passed to the data attribute, the Node corresponding to the node, and the node component itself.

Tree control node-click method after clicking will pass three parameters, usually just print the first in console.log will find that only label keyword information, need to obtain the subset or parent information are not, then you need to pass, print the second parameter Node, where you will find a lot of useful information. Using the method of changing icons, I use the author, but I find that after using custom icons, there are menu alignment problems, with and without subsets, the way is to let them all have icons, and then judge whether there is a subset. Make the transparency of the tree menu without a subset 0.

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MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b39ff0-2c1e2.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b39ff0-2c1e2.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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