将数组对象相同的key合并，主要判断合并其中字段的true和false

Question

请问怎么将对象相同的key合并，但是还要判断isIn字段存在true就为true，否则就为false

[
    {
        "favoriteId": 1,
        "favoriteName": "31的收藏夹",
        "isIn": true
    },
    {
        "favoriteId": 1,
        "favoriteName": "31的收藏夹",
        "isIn": false
    },
    {
        "favoriteId": 2,
        "favoriteName": "31的收藏夹2",
        "isIn": false
    },
    {
        "favoriteId": 2,
        "favoriteName": "31的收藏夹2",
        "isIn": true
    },
    {
        "favoriteId": 5,
        "favoriteName": "31的收藏夹3",
        "isIn": false
    }
]

变为下面这样

[
    {
        "favoriteId": 1,
        "favoriteName": "31的收藏夹",
        "isIn": true
    },
    {
        "favoriteId": 2,
        "favoriteName": "31的收藏夹2",
        "isIn": true
    },
    {
        "favoriteId": 5,
        "favoriteName": "31的收藏夹3",
        "isIn": false
    }
]

Answer 1

徒手写的，大概这样：

arr.reduce((accumulator, current) => {
    var val = accumulator.find(e => e.favoriteId === current.favoriteId);
    if (!!val) {
        if (current.isIn) {
            val.isIn = true;
        }
        return accumulator;
    }

    return accumulator.concat(current);
}, []);

Answer 2

lodash啊，神器在手，天下我有，一行代码搞定：

_.uniqBy(array.filter(item => item.isIn), 'favoriteId')