数据去重，笔试题系列

const arr = [
    {id: 0,pid: 1,order: 2,},
    { id: 0,pid: 1,order: 2 },
    {id: 0, pid: 1,order: 3,},
    {id: 1,pid: 1,order: 3,},
    {id: 2,pid: 2,order: 5,},
    {id: 3,pid: 2,order: 4,}
];

[
  { id: 0, pid: 1, order: 2 },
  { id: 1, pid: 1, order: 3 },
  { id: 2, pid: 2, order: 5 },
  { id: 3, pid: 2, order: 4 }
]

const quchong = (arr) => {
    const ret = [], obj = {};
    arr.forEach(v => {
        // if (!obj[v.id]) {
        //     ret.push(v)
        // }
        /**
         * 与下面等价
         */
        if (!Reflect.has(obj, v.id)) {
            ret.push(v)
        }
        obj[v.id] = v.id;
    })
    return ret.sort((a, b) => a.id - b.id);
}

const quchong2 = (arr) => {
    return arr.reduce((cur, prev) => {
        if (cur.findIndex(v => v.id === prev.id) === -1) {
            cur.push(prev)
        }
        return cur.sort((a, b) => a.id - b.id);
    }, [])
}

const quchong3 = (arr) => {
    const arrId = [...new Set(arr.map(v => v.id))];
    return arrId.reduce((cur, id) => {
        if (!cur[id]) {
            cur[id] = arr.find(v => v.id === id)
        }
        return Object.values(cur).sort((a, b) => a.id - b.id)
    }, {})
}

const quchong4 = (arr, map = new Map()) => {
    arr.forEach(v => {
        if (!map.has(v.id)) {
            map.set(v.id, v)
        }
    });
    return Object.values(map).sort((a, b) => a.id - b.id)
}
console.log('quchong1:', quchong(arr));
console.log('quchong2:', quchong2(arr));
console.log('quchong3:', quchong3(arr));
console.log('quchong4:', quchong4(arr));