Experience records on the use of high-order function reduce

1. Background:

var a = [
{
    name：'张三，李四',
personId:'111,222',
    id:'1'
},{
    name:'王五'，
personId:'333',
    id:'2'
}
];
var b = [
{
    name:'张三'，
    personId：'111',
    id:'1'
},{
    name:'李四'，
    personId：'222',
    id:'1'
}，{
    name:'王五'，
    personId：'333',
    id:'2'
},{
    name:'王六'，
    personId：'444',
    id:'3'
}
]；

After the b array is updated, if you want to get a new a array, merge the name field and personId field of data with the same ID, and splice them with ',';

2. Think of the high-order function reduce

3. Code judgment logic

var brr = brr.concat(arr);
var obj = {};
var b = [];
b = brr.reduce(function(item,next){
                if(obj[next.id]){
                    for(var k=0;k<item.length;k++){
                        if(item[k].id == next.id){
                            var flag = '0';
                            var crr = item[k].personId.split(',');
                            for(var i=0;i<crr.length;i++){
                                if(crr[i] == next.personId){
                                    flag = '1';
                                }
                            }
                            if(flag == '0'){
                                item[k].name= item[k].name+','+next.name;
                                item[k].personId= item[k].personId+','+next.personId;
                            }
                        }
                    }
                }else{
                    obj[next.id] = true && item.push(next);
                }
                return item;
            },[]);

This not only fulfills the requirements, but also ensures that the data will not be spliced ​​repeatedly.

That’s it, just record it like this, higher-order functions are delicious! ! ! ! ! ! ! ! ! ! ! !