javascript - 按 id 对对象数组进行分组

Question

我正在尝试遍历数组 ob 对象并将数组的项目分组到具有匹配 id 的新数组中:

API 示例:

    api_array [
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   ];

我正在努力实现这个结果:

result [
group_one [
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
]
group_two [
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
]
group_three [
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
]
group_four [
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
]
]

我实际上已经设法实现了它，但我认为这很疯狂，并且我确信这里有更好的实现是我所做的:

const createAddresses = (address) => {


        let group_one= [],
        group_two = [],
        group_three = [],
        group_four = [],
          group = [];

        debugger;
        for(let i=0; i < address.length; i++) {             
            switch (address[i].id) {
                case 1:
                        group_one.push(address[i]);
                    break;
                case 2:
                        group_two.push(address[i]);
                    break;
                case 3:
                        group_three.push(address[i]);
                    break;
                case 4:
                        group_four.push(address[i]);
                    break;
                default:
                    return address;                
            }
        }



        console.log('GROUP', group);
        return group.push(group_one, group_two, group_three, group_four);
    }

我真的不喜欢这个实现并且试过这个:

const obj = address.reduce((acc, cur) => ({...acc, [cur.id]: cur}), {});

上面的操作与我疯狂的 for 循环函数相同，但它只为每个组添加最后一个元素，如下所示:

result [
    0 [
           {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    ]
    1 [
           {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    ]
    2 [
           {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    ]
    3 [`enter code here`
           {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    ]
    ]

但正如我所提到的，我需要每个组中的所有元素，请提供任何建议。

Answer 1

按id分组对象数组

//Create a javascript array of objects containing key value pairs id, post 
var api_array = [ 
       {id: 1, postcode: '10'}, 
       {id: 1, postcode: '11'}, 
       {id: 2, postcode: '20'}, 
       {id: 2, postcode: '21'}, 
       {id: 2, postcode: '22'}, 
       {id: 3, postcode: '30'} 
   ];  
//result is a javascript array containing the groups grouped by id. 
let result = []; 

//javascript array has a method foreach that enumerates keyvalue pairs. 
api_array.forEach(  
    r => { 
        //if an array index by the value of id is not found, instantiate it. 
        if( !result[r.id] ){  
            //result gets a new index of the value at id. 
            result[r.id] = []; 
        } 
        //push that whole object from api_array into that list 
        result[r.id].push(r); 
    }   
); 
console.log(result[1]); 
console.log(result[2]); 
console.log(result[3]);

打印:

[ { id: 1, postcode: '10' }, { id: 1, postcode: '11' } ]

[ { id: 2, postcode: '20' }, 
  { id: 2, postcode: '21' },
  { id: 2, postcode: '22' } ]

[ { id: 3, postcode: '30' } ]