javascript - Groupby 不使用下划线 js

Question

我有一个按 ID 分组的集合。每个 id 包含对象数组。我想遍历它并创建一个目标集合，它将按“Id”列分组，如示例所示。我不会使用下划线js。我必须使用 javascript reduce 方法来实现这一点。

var targetCollection = [{
    123456: [
        { "Id": "1", "name": "xxx", "age": "22" },
        { "Id": "1", "name": "yyy", "age": "15" },
        { "Id": "5", "name": "zzz", "age": "59" }
    ],
    789456: [
        { "Id": "1", "name": "xxx", "age": "22" },
        { "Id": "1", "name": "yyy", "age": "15" },
        { "Id": "5", "name": "zzz", "age": "59" }
    ]
}]

var targetOutput = [{
    123456: {
        1: [{ "Id": "1", "name": "xxx", "age": "22" }, { "Id": "1", "name": "yyy", "age": "15" }],
        5: [{ "Id": "5", "name": "zzz", "age": "59" }]
    },
    789456: {
        1: [{ "Id": "1", "name": "xxx", "age": "22" }, { "Id": "1", "name": "yyy", "age": "15" }],
        5: [{ "Id": "5", "name": "zzz", "age": "59" }]
    }
}]

Code Snippet I have tried which didn't work

var newArray = [];
$.each(targetCollection, function (key, value) {
    var newTarget = $(this);
    var targetCollectionNew = newTarget.reduce(function (result, current) {
        result[current.ParentAreaID] = result[current.ParentAreaID] || [];
        result[current.ParentAreaID].push(current);
        return result;
    }, {});

    newArray.push(targetCollectionNew);
});

console.log('newArray', newArray);

我试过使用数组归约方法，但没有成功。请帮我。

Answer 1

你最初尝试的问题是你需要有两个循环，因为在第一个循环中 newValue 是一个对象而不是数组，所以没有 reduce 方法在上面。

更简单的解决方案是使用 map(您可以使用 forEach 或 $.each)并在第二个循环中减少(我使用简单的 for-in )。

像这样:

var targetCollection = [{
    123456: [
        { "Id": "1", "name": "xxx", "age": "22" },
        { "Id": "1", "name": "yyy", "age": "15" },
        { "Id": "5", "name": "zzz", "age": "59" }
    ],
    789456: [
        { "Id": "1", "name": "xxx", "age": "22" },
        { "Id": "1", "name": "yyy", "age": "15" },
        { "Id": "5", "name": "zzz", "age": "59" }
    ]
}];

var result = targetCollection.map(function(obj) {
    for (var key in obj) {
        obj[key] = obj[key].reduce(function(prev, curr) {
            if (!prev[curr.Id]) prev[curr.Id] = [];
            prev[curr.Id].push(curr);
            return prev;
        }, {});
    }
    return obj;
});

document.write('<pre>' + JSON.stringify(result, null, 4) + '</pre>');