vue与ant-tree结合伪造懒加载并可以查询

功能：
1、树懒加载
2、查询
3、关键字高亮显示
4、初始化加载展开4层

构造原因：ant-tree异步加载数据查询之后，节点不支持再次请求数据，直接渲染全部节点后，数据量特别大（生成dom进行操作），会造成浏览器卡顿

思路：
1、switcherIcon重写自定义树节点的展开/折叠图标
2、通过loaded状态判断是否完成了懒加载，当懒加载进行时，用loading状态更改图标
3、每次懒加载之后，给数据新建一个空的子节点，进行伪造懒加载（只有节点下有孩子节点时，才会有图标）

view视图

<a-input-search @search="onSearch" v-model.trim="searchStr"></a-input-search>
<a-tree
    @select="onSelect"
    :selectedKeys="selectedKeys"
    :treeData="treeData"
    :expandedKeys="expandedKeys"
    @expand="changeExpand"
    :replaceFields="{key:'id',title:'title',children:'children'}"
        >
    <template slot="switcherIcon" slot-scope="{loading}">
        <a-icon type="caret-down" v-if="loading"></a-icon>
        <a-icon type="loading" v-else></a-icon>
    </template>
    <template slot="title" slot-scope="{title}">
        <span v-html="
          title 
          ? title.replace(
            new RegExp(replaceKeywords,g),
            '<span style=color:#f50>'+title+'</span>'
            )
          : null"
        ></span>
    </template>
</a-tree>

加载树
loadingData为最后展开的一层节点，方便首次加载默认展开层级

async loadTree(treeId,treeNode,isSearch){
    let params={treeId}
    let [err,res] = await loadTree(params);
    if(!err){
        if(res.result.code == 200){
            //存在树节点
            if(treeId){
                treeNode.dataRef.children = this.getUpdateTree(res.result.data);
                this.treeData = [...this.treeData];
                this.loadingData = res.result.data
            }else{
                if(isSearch){
                    this.treeData = res.result.data;
                    this.expandedKeys = [];
                    this.getAllKey(this.treeData)
                }else{
                    this.treeData = this.getUpdateTree(res.result.data);
                    if(!this.treeData.length){return;}
                    //首次加载默认加载到第四层
                    this.expandedKeys = []
                    this.initTree(this.treeData,1,4)
                }
            }
        }
    }
}

initTree：初始化循环树，默认展示到第几层

async initTree(treeData,index,maxLevel){
    if(index > maxLevel || !treeData.length){return};
    treeData.map(item=>{
        if(item.childrenIds.length){
            let initLoaded = item.loaded;
            item.loaded = true;
            item.loading = true;
            let data = {dataRef:item}
            if(initLoaded){
                index++;
                treeData = item.children
                this.initTree(treeData,index,maxLevel);
                item.loading = false;
                this.expandedKeys.push(item.id);
                return;
            }
            setTimeOut(
                async ()=>{
                    let returnData = await this.onLoadData(data);
                    if(returnData.length){
                        index++;
                        treeData = this.loadingData;
                        this.initTree(treeData,index,maxLevel);
                        item.loading = false;
                        this.expandedKeys.push(item.id);
                    }
                },
                initLoaded ? 0 :100
            )
        }
    })
}

onLoadData：懒加载

onLoadData(treeNode){
    return new Promise(resolve=>{
        setTimeout(()=>{
            treeNode.dataRef.loading = false;
            resolve(this.loadTree(treeNode.dataRef.id,treeNode))
        },10)
    })
}

getUpdateTree：添加一个空数组，伪造懒加载

getUpdateTree(data){
    data.map(item=>{
        if(存在子节点){
            item.children = [{}]
        }
    })
}

getAllKey：获取树节点所有的key

getAllKey(data){
    data.map(item=>{
        this.expandedKeys.push(item.id);
        if(item.children){
            this.getAllKey(item.children)
        }
    })
}

onSearch：搜索

onSearch(){
    this.expandedKey = []
    this.searchKeywords = this.searchStr;
    //替换特殊字符
    this.replaceKeywords = this.searchStr.split("\\").join("\\\\");
    this.replaceKeywords = this.replaceKeywords.split("[").join("\\[");
    this.replaceKeywords = this.replaceKeywords.split("]").join("\\]");
    this.replaceKeywords = this.replaceKeywords.split("$").join("\\$");
    this.replaceKeywords = this.replaceKeywords.split("^").join("\\^");
    this.replaceKeywords = this.replaceKeywords.split("*").join("\\*");
    this.replaceKeywords = this.replaceKeywords.split("(").join("\\(");
    this.replaceKeywords = this.replaceKeywords.split(")").join("\\)");
    this.replaceKeywords = this.replaceKeywords.split("+").join("\\+");
    this.replaceKeywords = this.replaceKeywords.split("|").join("\\|");
    this.replaceKeywords = this.replaceKeywords.split("?").join("\\?");
    this.loadTree("","",true)
}

changeExpand：点击判断是否异步加载

changeExpand(event,node){
    if(node.node.dataRef.loaded){
        this.expandedKeys = event;
        return;
    }
    node.node.dataRef.loading = true;//添加懒加载效果
    node.node.dataRef.loaded = true;//当点击时，表示已经加载
    this.onLoadData(node.node);
    this.expandedKeys = event
}