js求对象数组的交集/并集/差集/去重

      1.求交集
　　　　var arr1 = [{name:'name1',id:1},{name:'name2',id:2},{name:'name3',id:3}];
      var arr1Id = [1,2,3]
      var arr2 = [{name:'name1',id:1},{name:'name2',id:2},{name:'name3',id:3},{name:'name4',id:4},{name:'name5',id:5}];
      var result = arr2.filter(function(v){
            return arr1Id.indexOf(v.id)!==-1 // 利用filter方法来遍历是否有相同的元素
        })
      console.log(result);

      2.求并集
　　　　let arr1 = [{name:'name1',id:1},{name:'name2',id:2},{name:'name3',id:3}];
      let arr2 = [{name:'name1',id:1},{name:'name4',id:4},{name:'name5',id:5}];
      let arr3 = arr1.concat(arr2);
      let result = [];
      var obj = [];
      result = arr3.reduce(function(prev, cur, index, arr) {
        console.log(prev, cur);
        obj[cur.id] ? '' : obj[cur.id] = true && prev.push(cur);
        return prev;
      }, []);
      console.log(result);

　　　　3.求差集
　　　　let arr1 = [{name:'name1',id:1},{name:'name2',id:2},{name:'name3',id:3}];
      let arr1Id = [1,2,3];
      let arr2 = [{name:'name1',id:1},{name:'name4',id:4},{name:'name5',id:5}];
      let arr2Id = [1,4,5];
      let arr3 = arr1.concat(arr2);
      let result = arr3.filter(function(v){
          return arr1Id.indexOf(v.id)===-1 || (arr2Id.indexOf(v.id)===-1)
      })
      console.log(result);

　　

      4.去重
　　　　let arr = [{name:'name1',id:1},{name:'name2',id:2},{name:'name3',id:3},{name:'name1',id:1},{name:'name4',id:4},{name:'name5',id:5}];
      var obj = [];
      let result = arr.reduce(function(prev, cur, index, arr) {
        console.log(prev, cur);
        obj[cur.id] ? '' : obj[cur.id] = true && prev.push(cur);
        return prev;
      }, []);

 实际组件中应用去重

　a方法

　　　　　　　let includeThis = false
            let vm = this
            if(vm.informedPersonList.length>0){
                vm.informedPersonList.forEach(el =>{
                    if(el.id == vm.selectedTrueItem.id){
                        includeThis = true
                    }
                })
            }
            if(includeThis===false){
                vm.informedPersonList.push(vm.selectedTrueItem)
            }else{
                Message({message: '请勿重复添加',type: 'warning'})
            }

　b方法(必须先let informedPersonL = vm.informedPersonList，不能直接使用vm.informedPersonList，否则浏览器控制台会报错)

            vm.informedPersonList.push(this.selectedTrueItem)
            let obj = {};
            let informedPersonL = vm.informedPersonList
            informedPersonL = informedPersonL.reduce((cur,next) => {
                obj[next.id] ? "" : obj[next.id] = true && cur.push(next);
                return cur;
            },[]) //设置cur默认类型为数组，并且初始值为空的数组
            vm.selectedTrueItem = {}
            vm.$emit("backInformedPList",informedPersonL);