数据处理为树形结构以及多级菜单的逻辑分析

function treeData(data){   
        let cloneData = JSON.parse(JSON.stringify(data))
        return cloneData.filter(father=>{
            let branchArr = cloneData.filter(child => father['id'] == child['pid']);
            branchArr.length>0 ? father['children'] = branchArr : '';
            return father['pid'] == 0 ;
        })
    }

function toTree(data) {
        let result = []
        if (!Array.isArray(data)) {
            return result
        }
        data.forEach(item => {
            delete item.children;
        });
        let map = {};
        data.forEach(item => {
            item.expand = false;
            map[item.id] = item;
        });
        data.forEach(item => {
            let parent = map[item.pid];
            if (parent) {
                (parent.children || (parent.children = [])).push(item);
            } else {
                result.push(item);
            }
        });
        return result;
    }

//数据源组装成树形结构（一级与后面的级逻辑不同）
逻辑：开始遍历所有数据，根据一级关系找出一级，调用二级方法；将2级方法抽离出来，在2级方法中遍历所有数据，并根据一级与2级的关系找出2级
function first（data，arr，0）{
for(var i =0;i<data.length;i++){
if(data[i].pid == 0){
arr.push(data[i]);
two(data,data[i].id);
}
}
}
function two (data,pid){
var arr = [];
for(var i = 0;i<data[i].length;i++){
if(data[i].pid == pid）{
arr.push(data[i])
}
}
return arr;
}