javascript - Underscore.js组按两个级别

我似乎无法正确地说出这句话，因为我需要按date和foo进行分组：

// Using date as numbers for clear example
// date key should be grouped into a key
// Under that key (date), I should see another key of "foo"

let list = [
  { date: "1", foo: "me", result: "meFoo"},
  { date: "1", foo: "me2", result: "meYou"},
  { date: "1", foo: "me3", result: "meHe"},
  { date: "2", foo: "me", result: "meHim"},
  { date: "2", foo: "me2", result: "meHim"}
]

let grouped = _.groupBy(list, "date") // keys ie 1, 2

// I need another key under the date key, possible?
let grouped = _.groupBy(list, "date", (val) => _.groupBy(val), "foo") // result not expected

我在这里有点复杂，所以我使用下划线来减轻复杂性。这可能吗？

然后，我将执行类似的操作，可以使用_.pluck：

Object.keys(grouped).map( dateKey => Object.keys(grouped[dateKey]).map(fooKey => console.log( grouped[dateKey][fookey][0] )) )

从最高层次看，这确实是错误的。

预期结果如下所示：

DATE // key
 |
 |___ FOO // key
       |
       |__ array foo objects

最佳答案

这将为您提供所需的阵列。

_.map(_.groupBy(list, 'date'), (value, key) => ({[key]: _.groupBy(value, 'foo')}))

我希望你想要这样的结果：

var list = [{ date: "1", foo: "me", result: "meFoo" }, { date: "1", foo: "me2", result: "meYou" }, { date: "1", foo: "me3", result: "meHe" }, { date: "2", foo: "me", result: "meHim" }, { date: "2", foo: "me2", result: "meHim" }],
    grouped = _.map(_.groupBy(list, 'date'), (value, key) => ({[key]: _.groupBy(value, 'foo')}));

console.log(grouped);

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