javascript - 按值排序对象未按预期工作

Question

我正在尝试根据 value.first_name 对 2 个对象进行排序。一个升序字母顺序。另一个降序字母顺序。但是，它们都是降序排序。我究竟做错了什么？目标是根据 first_name 的值排列此数组中的对象。

var participants = [
  {
    id: "992543",
    first_name: "",
    last_name: "",
    company: null,
    notes: "",
    registrationType: "",
    alerts: [ ],
    reg_scan: null
  },
  {
    id: "999070",
    first_name: "Tori",
    last_name: "Fullard",
    company: null,
    notes: "",
    registrationType: "Staff",
    alerts: [ ],
    reg_scan: null
  },
  {
    id: "99265",
    first_name: "Ronald",
    last_name: "Brown",
    company: null,
    notes: "",
    registrationType: "Dean's Guest",
    alerts: [ ],
    reg_scan: null
  },
  {
    id: "992279",
    first_name: "Laila",
    last_name: "Shetty",
    company: null,
    notes: "",
    registrationType: "Table Guest",
    alerts: [
      {
        alert_id: "1",
        dismissed: "0"
      }
    ],
    reg_scan: null
    },
    {
    id: "992248",
    first_name: "Paul",
    last_name: "Keenan",
    company: null,
    notes: "",
    registrationType: "Table Guest",
    alerts: [ ],
    reg_scan: null
    }
    ];

var az_part = participants;
var za_part = participants;
az_part.sort(function(a, b) {
    var nameA = a.first_name.toLowerCase();
    var nameB = b.first_name.toLowerCase();
    if (nameA > nameB) return 1;
    if (nameA < nameB) return -1;
    return 0;
});

za_part.sort(function(a, b) {
    var nameA = a.first_name.toLowerCase();
    var nameB = b.first_name.toLowerCase();
    if (nameA > nameB) return -1;
    if (nameA < nameB) return 1;
    return 0;
});

Answer 1

所有三个变量 az_part、za_part 和 participants 都引用内存中完全相同的数组。您正在使用升序转换该数组，然后立即使用降序对其重新排序。

使用 slice 创建数组的浅拷贝:

var az_part = participants.slice();
var za_part = participants.slice();

(“浅拷贝”我的意思是这将创建一个新列表，但它不会创建新对象。每个结果列表将不同——并且可以不同排序——但如果你改变任何对象在内部，例如 participants[2].notes = "foo"，这将改变每个列表中存在的对象。)