JavaScript array.sort 具有多个值（字符串和数字）

Question

我想按主题 (string, Alphabetical)对数组进行排序，然后按级别 (int, ascending)排序，然后按名称 (string, Alphabetical) 排序。我在 SO 上找到了许多其他线程，但没有找到任何按多个变量类型排序的线程。我以为我有它，但它没有正确排序。

排序函数：

scipads.sort(function (a, b) {
    if (a.subject != b.subject)
        return a.subject < b.subject;
    if (a.level != b.level)
        return a.level - b.level;
    return a.name < b.name;
});

数组：

var scipads = [{
        "name": "L2 Physics Externals",
        "level": 2,
        "subject": "physics",
    }, {
        "name": "L2 Physics Internals",
        "level": 2,
        "subject": "physics",
    }, {
        "name": "L2 Chem Externals",
        "level": 2,
        "subject": "chemistry",
    }, {
        "name": "L2 Chem Internals",
        "level": 2,
        "subject": "chemistry",
    }, {
        "name": "L2 Bio Internals",
        "level": 2,
        "subject": "biology",
    }, {
        "name": "L2 Bio Externals",
        "level": 2,
        "subject": "biology",
    }, {
        "name": "L1 Electricity & Magnetism",
        "level": 1,
        "subject": "physics",
    }, {
        "name": "L1 Wave Behaviour",
        "level": 1,
        "subject": "physics",
    }, {
        "name": "L1 Heat",
        "level": 1,
        "subject": "physics",
    }, {
        "name": "L1 Carbon Chemistry",
        "level": 1,
        "subject": "chemistry",
    }, {
        "name": "L1 Selected Elements",
        "level": 1,
        "subject": "chemistry",
    }, {
        "name": "L1 Chemical Reactions",
        "level": 1,
        "subject": "chemistry",
    },
];

如何按主题、级别、名称排序？

Answer 1

用于localeCompare比较字符串

var scipads=[{name:"L2 Physics Externals",level:2,subject:"physics"},{name:"L2 Physics Internals",level:2,subject:"physics"},{name:"L2 Chem Externals",level:2,subject:"chemistry"},{name:"L2 Chem Internals",level:2,subject:"chemistry"},{name:"L2 Bio Internals",level:2,subject:"biology"},{name:"L2 Bio Externals",level:2,subject:"biology"},{name:"L1 Electricity & Magnetism",level:1,subject:"physics"},{name:"L1 Wave Behaviour",level:1,subject:"physics"},{name:"L1 Heat",level:1,subject:"physics"},{name:"L1 Carbon Chemistry",level:1,subject:"chemistry"},{name:"L1 Selected Elements",level:1,subject:"chemistry"},{name:"L1 Chemical Reactions",level:1,subject:"chemistry"}];

scipads.sort(function(a, b) {
  if (a.subject != b.subject)
    return a.subject.localeCompare(b.subject);
  else if (a.level != b.level)
    return a.level - b.level;
  return a.name.localeCompare(b.name);
});

console.log(scipads);