我如何操纵Javascript数组？

Question

我想用样本数据操作数组。

我想要做的是在投票数据中找到movieId，统计它，获取用户的名字

数据说明：

movieId：投票有多个movieIds，但只需要导入一个。

movieIdLength：movieId的总数。

name：具有相同movieId的用户名。

例如：

var votes = [{

    "id": 1,
    "pollId": 1,
    "movieId": 2,
    "name": "James"
}, {
    "id": 2,
    "pollId": 1,
    "movieId": 3,
    "name": "Laura"
}, {
    "id": 3,
    "pollId": 1,
    "movieId": 1,
    "name": "Dan"
}, {
    "id": 4,
    "pollId": 1,
    "movieId": 3,
    "name": "Steve"
}]

我想要的是什么：

var votesResult = [{

    "movieId": 2,
    "movieIdLength": 1,
    "name": "James"
},{
    "movieId": 1,
    "movieIdLength": 1,
    "name": "Dan"
},{
    "movieId": 3,
    "movieIdLength": 2,
    "name": "Laura, Steve"
}]

Answer 1

ES6：

const a = [{
    "id": 1,
    "pollId": 1,
    "movieId": 2,
    "name": "James"
}, {
    "id": 2,
    "pollId": 1,
    "movieId": 3,
    "name": "Laura"
}, {
    "id": 3,
    "pollId": 1,
    "movieId": 1,
    "name": "Dan"
}, {
    "id": 4,
    "pollId": 1,
    "movieId": 3,
    "name": "Steve"
}]

const r = [...new Set(a.map(x => x.movieId))]
	.map(x => Object.assign({movieId: x}, 
  	{movieIdLength: a.filter(l => l.movieId === x).length}, 
  	{name: a.filter(q => q.movieId === x).map(n => n.name).join(', ')}));

console.log(JSON.stringify(r, null, 2));

不太清楚，但没有代码重复：

const a = [{
    "id": 1,
    "pollId": 1,
    "movieId": 2,
    "name": "James"
}, {
    "id": 2,
    "pollId": 1,
    "movieId": 3,
    "name": "Laura"
}, {
    "id": 3,
    "pollId": 1,
    "movieId": 1,
    "name": "Dan"
}, {
    "id": 4,
    "pollId": 1,
    "movieId": 3,
    "name": "Steve"
}]

const r = [...new Set(a.map(x => x.movieId))]
  .map(x => Object.assign({movieId: x}, 
  ((f) => Object.assign({movieIdLength: f.length, name: f.map(({name}) => name).join(', ')})
    )(a.filter(({movieId}) => movieId === x))
  ));

console.log(JSON.stringify(r, null, 2));