作用:

可以用来将数据组合成树形的数据,可以像操作单独的对象一样去操作整个树形结构

树是相对复杂的数据,使用组合模式去封装树形的组件,是很重要的,可以对外暴露很多树的操作方法

示例:

        //一个树型的对象数据
        class Organ {
            constructor(label, value, parentName) {
                this.label = label
                this.value = value
                this.parentName = parentName
                this.childRen = []
            }
        }
        //新增元素
        Organ.prototype.addChildRen = function () {
            let arr = Array.from(arguments)
            arr.forEach(item => {
                this.childRen.push(item)
                this.flatList.push([this.value,item.value])
            })
            this.changeTreeNodeList()
        }
        //删除某个元素,其子节点也都会被一并删除
        Organ.prototype.removeChildRen = function (nodeValue) {
            let index = this.childRen.findIndex(val => val.value === nodeValue)
             this.childRen.splice(index,1)
             let arr = this.flatList.map(item=>{
                if(!item.includes(nodeValue)){
                    return item
                }
             })
            this.flatList = arr.filter(item => item !== undefined)
            this.changeTreeNodeList()
        }
        //过滤生成树的各条节点路线
        Organ.prototype.changeTreeNodeList = function(){
            this.treeNodeList.length = 0
            this.flatList.forEach(item1=>{
                let obj = this.flatList.find(item2 => item2[item2.length-1] === item1[0])
                if(obj){
                  this.treeNodeList.push([... new Set([].concat(obj).concat(item1))])
                }
            })
        }
        Organ.prototype.flatList = []
        Organ.prototype.treeNodeList = []

        //创建父级组织
        const jituanjun1 = new Organ('第一集团军','jituanjun1',false)
        //创建子级组织
        const hechenglv1 = new Organ('合成1旅','hechenglv1','jituanjun1')
        const hechenglv2 = new Organ('合成2旅', 'hechenglv2','jituanjun1')
        //子级组织加入父级组织
        jituanjun1.addChildRen(hechenglv1, hechenglv2)

        //下面操作重复上面的操作
        const bubingying1 = new Organ('步兵1营', 'bubingying1','hechenglv1')
        const bubingying2 = new Organ('步兵2营', 'bubingying2','hechenglv1')
        hechenglv1.addChildRen(bubingying1,bubingying2)
        const bubingying3 = new Organ('步兵3营', 'bubingying3','hechenglv2')
        const bubingying4 = new Organ('步兵4营', 'bubingying4','hechenglv2')
        hechenglv2.addChildRen(bubingying3,bubingying4)
        const bubingying5 = new Organ('步兵5营', 'bubingying5','hechenglv2')
        hechenglv2.addChildRen(bubingying5)

        //撤编
        hechenglv2.removeChildRen('bubingying4')
        console.log(jituanjun1,'第一集团军编制')
        console.log(jituanjun1.treeNodeList,'树的所有完整节点流向')