JavaScript 按 2 个值对数组排序

Question

我有一个数组，我想按 "id" 和 "date" 从小到大对它进行排序。我怎样才能正确地做到这一点？

示例：

var unsorted = [
    {id: 1, date: "2015-01-18T15:00:00+01:00"}, 
    {id: 1, date: "2015-01-18T14:30:00+01:00"}, 
    {id: 2, date: "2015-01-18T10:00:00+01:00"}, 
    {id: 1, date: "2015-01-18T16:00:00+01:00"}, 
    {id: 3, date: "2015-01-18T14:15:00+01:00"}, 
    {id: 2, date: "2015-01-18T14:00:00+01:00"}
]

应该return：

var sorted = [
    {id: 1, date: "2015-01-18T14:30:00+01:00"}, 
    {id: 1, date: "2015-01-18T15:00:00+01:00"}, 
    {id: 1, date: "2015-01-18T16:00:00+01:00"}, 
    {id: 2, date: "2015-01-18T10:00:00+01:00"}, 
    {id: 2, date: "2015-01-18T14:00:00+01:00"},
    {id: 3, date: "2015-01-18T14:15:00+01:00"} 
]

Answer 1

您可以使用 .sort():

var unsorted = [
    {id: 1, date: "2015-01-18T15:00:00+01:00"}, 
    {id: 1, date: "2015-01-18T14:30:00+01:00"}, 
    {id: 2, date: "2015-01-18T10:00:00+01:00"}, 
    {id: 1, date: "2015-01-18T16:00:00+01:00"}, 
    {id: 3, date: "2015-01-18T14:15:00+01:00"}, 
    {id: 2, date: "2015-01-18T14:00:00+01:00"}
];

var sorted = unsorted.sort(function(a, b) {
    return a.id == b.id ?
        new Date(a.date) - new Date(b.date) : a.id - b.id;
});

console.log(sorted);

输出：

[ { id: 1, date: '2015-01-18T14:30:00+01:00' },
  { id: 1, date: '2015-01-18T15:00:00+01:00' },
  { id: 1, date: '2015-01-18T16:00:00+01:00' },
  { id: 2, date: '2015-01-18T10:00:00+01:00' },
  { id: 2, date: '2015-01-18T14:00:00+01:00' },
  { id: 3, date: '2015-01-18T14:15:00+01:00' } ]

Answer 2

Array.sort 采用带有两个参数的函数来比较数组的两个元素。如果此函数 returns 为负数，则 a 位于 b 之前，如果为 returns 正数，则 a 位于 b 之前，如果为 returns 0，则它们保持原样。在这里，我按 ID 比较它们，如果它们的 ID 相同，则我按日期比较它们。

var unsorted = [{
  id: 1,
  date: "2015-01-18T15:00:00+01:00"
}, {
  id: 1,
  date: "2015-01-18T14:30:00+01:00"
}, {
  id: 2,
  date: "2015-01-18T10:00:00+01:00"
}, {
  id: 1,
  date: "2015-01-18T16:00:00+01:00"
}, {
  id: 3,
  date: "2015-01-18T14:15:00+01:00"
}, {
  id: 2,
  date: "2015-01-18T14:00:00+01:00"
}];

unsorted.sort(function(a, b) {
  if (a.id < b.id)
    return -1;
  else if (a.id > b.id)
    return 1;
  else {
    if (a.date < b.date)
      return -1;
    else if (a.date > b.date)
      return 1;
    else
      return 0;
  }
});

Answer 3

试一试

var sorted = unsorted.sort(function(a, b) {
    return a.id === b.id ?
      Date.parse(a.date) - Date.parse(b.date) :
      a.id - b.id ;
});

说明

如果id字段相等，我们要return比较date字段

如果id字段不相等，我们将return比较id字段

Answer 4

这是一个使用 array.sort 的例子：

var arr = [
    {id: 1, date: "2015-01-18T15:00:00+01:00"}, 
    {id: 1, date: "2015-01-18T14:30:00+01:00"}, 
    {id: 2, date: "2015-01-18T10:00:00+01:00"}, 
    {id: 1, date: "2015-01-18T16:00:00+01:00"}, 
    {id: 3, date: "2015-01-18T14:15:00+01:00"}, 
    {id: 2, date: "2015-01-18T14:00:00+01:00"}
];

arr.sort(function(a,b){
    if (a.id == b.id) return a.date.localeCompare(b.date);
    return a.id-b.id;    
});

// test
for (var i in arr) {
    console.log(arr[i]);
}

结果为：

 Object {id: 1, date: "2015-01-18T14:30:00+01:00"}
 Object {id: 1, date: "2015-01-18T15:00:00+01:00"}
 Object {id: 1, date: "2015-01-18T16:00:00+01:00"}
 Object {id: 2, date: "2015-01-18T10:00:00+01:00"}
 Object {id: 2, date: "2015-01-18T14:00:00+01:00"}
 Object {id: 3, date: "2015-01-18T14:15:00+01:00"}

Answer 5

分而治之！

首先将输入数组缩减为 id => object 的映射，即：

var dataById = unsorted.reduce(function (soFar, value) {
 // Initialise the array if we haven't processed this
    // id yet.
    if (soFar[value.id] === undefined) {
        soFar[value.id] = [];
    }
  
    // ad this object to Array.
    soFar[value.id].push(value);
  
    return soFar;
}, {});

现在您可以通过遍历对象的键对每个数组进行排序，请注意这会修改 dataById 映射。

Object.keys(dataById).forEach(function (id) {
 dataById[id] = dataById[id].sort();
});

最后，您可以再次通过遍历映射中的键将所有数据组合在一起。请注意 javascript 中的映射（对象）不保证其键的顺序，因此您可能希望在迭代之前先将 ID 转储到数组中：

var ids = Object.keys(dataById).sort();

// Reduce the ids into an Array of data.
var ids.reduce(function (soFar, value) {
 return soFar.concat(dataById[id]);
}, []);

这不是解决问题的最有效方法，但希望它能对您的思考过程有所帮助。

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