转载：https://www.cnblogs.com/rysinal/p/5834446.html

希望的是将下面的对象数组：

[
    {"id":"1001","name":"值1","value":"111"},
    {"id":"1001","name":"值1","value":"11111"},
    {"id":"1002","name":"值2","value":"25462"},
    {"id":"1002","name":"值2","value":"23131"},
    {"id":"1002","name":"值2","value":"2315432"},
    {"id":"1003","name":"值3","value":"333333"}
]

 根据相同id字段分组，转换成下面这种形式：

[
    {
        "id": "1001",
        "name": "值1",
        "data": [
            {"id": "1001", "name": "值1", "value": "111"},
            { "id": "1001", "name": "值1", "value": "11111"}
        ]
    },
    {
        "id": "1002",
        "name": "值2",
        "data": [
            { "id": "1002",  "name": "值2", "value": "25462" },
            { "id": "1002", "name": "值2", "value": "23131"},
            {"id": "1002", "name": "值2","value": "2315432" }
        ]
    },
    {
        "id": "1003",
        "name": "值3",
        "data": [
            {"id": "1003", "name": "值3", "value": "333333" }
        ]
    }
]

 做法：

var arr = [
    {"id":"1001","name":"值1","value":"111"},
    {"id":"1001","name":"值1","value":"11111"},
    {"id":"1002","name":"值2","value":"25462"},
    {"id":"1002","name":"值2","value":"23131"},
    {"id":"1002","name":"值2","value":"2315432"},
    {"id":"1003","name":"值3","value":"333333"}
];

var map = {},
    dest = [];
for(var i = 0; i < arr.length; i++){
    var ai = arr[i];
    if(!map[ai.id]){
        dest.push({
            id: ai.id,
            name: ai.name,
            data: [ai]
        });
        map[ai.id] = ai;
    }else{
        for(var j = 0; j < dest.length; j++){
            var dj = dest[j];
            if(dj.id == ai.id){
                dj.data.push(ai);
                break;
            }
        }
    }
}

console.log(dest);