从这个最初的问题,我将如何在多个字段应用排序?

使用这种稍作调整的结构,我将如何排序城市(上升)和价格(下降)?

var homes = [
    {"h_id":"3",
     "city":"Dallas",
     "state":"TX",
     "zip":"75201",
     "price":"162500"},
    {"h_id":"4",
     "city":"Bevery Hills",
     "state":"CA",
     "zip":"90210",
     "price":"319250"},
    {"h_id":"6",
     "city":"Dallas",
     "state":"TX",
     "zip":"75000",
     "price":"556699"},
    {"h_id":"5",
     "city":"New York",
     "state":"NY",
     "zip":"00010",
     "price":"962500"}
    ];

我喜欢的事实是,给出的答案提供了一个一般的方法。在我计划使用这段代码的地方,我将不得不对日期以及其他东西进行排序。“启动”对象的能力似乎很方便,如果不是有点麻烦的话。

我试图把这个答案构建成一个很好的通用示例,但我运气不太好。


当前回答

这是一个完全的欺骗,但我认为它为这个问题增加了价值,因为它基本上是一个罐装的库函数,你可以开箱即用。

如果你的代码可以访问lodash或者一个与lodash兼容的库,比如下划线,那么你可以使用_。sortBy方法。下面的代码片段直接复制自lodash文档。

示例中的注释结果看起来像是返回数组的数组,但这只是显示了顺序,而不是实际的结果,它是一个对象数组。

var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 },
  { 'user': 'barney', 'age': 34 }
];

_.sortBy(users, [function(o) { return o.user; }]);
 // => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]

_.sortBy(users, ['user', 'age']);
// => objects for [['barney', 34], ['barney', 36], ['fred', 40], ['fred', 48]]

其他回答

这里' affiliation duedate '和'Title'是列,两者都是升序排序。

array.sort(function(a, b) {

               if (a.AffiliateDueDate > b.AffiliateDueDate ) return 1;
               else if (a.AffiliateDueDate < b.AffiliateDueDate ) return -1;
               else if (a.Title > b.Title ) return 1;
               else if (a.Title < b.Title ) return -1;
               else return 0;
             })

只需遵循排序标准列表

即使要封装36个排序标准,这段代码也将始终保持可读和可理解

Nina在这里提出的解决方案当然非常优雅,但它意味着要知道在布尔逻辑中,值为0对应的值为false,并且布尔测试在JavaScript中可以返回除true / false以外的值(这里是数值),这对于初学者来说总是令人困惑。

还要考虑谁需要维护您的代码。也许会是你:想象一下你自己花了几天的时间在另一个人的代码上,然后有了一个有害的错误……你读了几千行充满技巧的文章,都累坏了

const homes = [ { h_id: '3', city: 'Dallas', state: 'TX', zip: '75201', price: '162500' } , { h_id: '4', city: 'Bevery Hills', state: 'CA', zip: '90210', price: '319250' } , { h_id: '6', city: 'Dallas', state: 'TX', zip: '75000', price: '556699' } , { h_id: '5', city: 'New York', state: 'NY', zip: '00010', price: '962500' } ] const fSort = (a,b) => { let Dx = a.city.localeCompare(b.city) // 1st criteria if (Dx===0) Dx = Number(b.price) - Number(a.price) // 2nd // if (Dx===0) Dx = ... // 3rd // if (Dx===0) Dx = ... // 4th.... return Dx } console.log( homes.sort(fSort))

这是一个递归算法,按多个字段排序,同时有机会在比较之前格式化值。

var data = [
{
    "id": 1,
    "ship": null,
    "product": "Orange",
    "quantity": 7,
    "price": 92.08,
    "discount": 0
},
{
    "id": 2,
    "ship": "2017-06-14T23:00:00.000Z".toDate(),
    "product": "Apple",
    "quantity": 22,
    "price": 184.16,
    "discount": 0
},
...
]
var sorts = ["product", "quantity", "ship"]

// comp_val formats values and protects against comparing nulls/undefines
// type() just returns the variable constructor
// String.lower just converts the string to lowercase.
// String.toDate custom fn to convert strings to Date
function comp_val(value){
    if (value==null || value==undefined) return null
    var cls = type(value)
    switch (cls){
        case String:
            return value.lower()
    }
    return value
}

function compare(a, b, i){
    i = i || 0
    var prop = sorts[i]
    var va = comp_val(a[prop])
    var vb = comp_val(b[prop])

    // handle what to do when both or any values are null
    if (va == null || vb == null) return true

    if ((i < sorts.length-1) && (va == vb)) {
        return compare(a, b, i+1)
    } 
    return va > vb
}

var d = data.sort(compare);
console.log(d);

如果a和b相等,它将尝试下一个字段,直到没有可用字段。

我喜欢snowburn的方法,但它需要调整来测试城市的等效性,而不是差异。

homes.sort(
   function(a,b){
      if (a.city==b.city){
         return (b.price-a.price);
      } else {
         return (a.city-b.city);
      }
   });

通过添加3个相对简单的帮助程序,可以构建一个非常直观的功能解决方案。在深入研究之前,我们先来了解一下用法:

function usage(homes, { asc, desc, fallback }) { homes.sort(fallback( asc(home => home.city), desc(home => parseInt(home.price, 10)), )); console.log(homes); } var homes = [{ h_id: "3", city: "Dallas", state: "TX", zip: "75201", price: "162500", }, { h_id: "4", city: "Bevery Hills", state: "CA", zip: "90210", price: "319250", }, { h_id: "6", city: "Dallas", state: "TX", zip: "75000", price: "556699", }, { h_id: "5", city: "New York", state: "NY", zip: "00010", price: "962500", }]; const SortHelpers = (function () { const asc = (fn) => (a, b) => (a = fn(a), b = fn(b), -(a < b) || +(a > b)); const desc = (fn) => (a, b) => asc(fn)(b, a); const fallback = (...fns) => (a, b) => fns.reduce((diff, fn) => diff || fn(a, b), 0); return { asc, desc, fallback }; })(); usage(homes, SortHelpers);

如果你向下滚动代码片段,你可能已经看到了helper:

const asc  = (fn) => (a, b) => (a = fn(a), b = fn(b), -(a < b) || +(a > b));
const desc = (fn) => (a, b) => asc(fn)(b, a);
const fallback = (...fns) => (a, b) => fns.reduce((diff, fn) => diff || fn(a, b), 0);

让我快速解释一下这些函数的作用。

asc creates a comparator function. The provided function fn is called for both the comparator arguments a and b. The results of the two function calls are then compared. -1 is returned if resultA < resultB, 1 is returned if resultA > resultB, or 0 otherwise. These return values correspond with an ascending order direction. It could also be written like this: function asc(fn) { return function (a, b) { // apply `fn` to both `a` and `b` a = fn(a); b = fn(b); if (a < b) return -1; if (a > b) return 1; return 0; // or `return -(a < b) || +(a > b)` for short }; } desc is super simple, since it just calls asc but swaps the a and b arguments, resulting in descending order instead of ascending. fallback (there might be a better name for this) allows us to use multiple comparator functions with a single sort. Both asc and desc can be passed to sort by themself. homes.sort(asc(home => home.city)) There is however an issue if you want to combine multiple comparator functions. sort only accepts a single comparator function. fallback combines multiple comparator functions into a single comparator. The first comparator is called with arguments a and b, if the comparator returns the value 0 (meaning that the values are equal) then we fall back to the next comparator. This continues until a non-0 value is found, or until all comparators are called, in which case the return value is 0.

也可以为fallback()提供自定义比较器函数。假设您想使用localeCompare()而不是比较字符串与<和>。在这种情况下,您可以将asc(home => home.city)替换为(a, b) => a.city.localeCompare(b.city)。

homes.sort(fallback(
  (a, b) => a.city.localeCompare(b.city),
  desc(home => parseInt(home.price, 10)),
));

需要注意的一点是,在与<和>比较时,未定义的值总是返回false。因此,如果一个值可能缺失,您可能希望首先根据它的存在进行排序。

homes.sort(fallback(
  // homes with optionalProperty first, true (1) > false (0) so we use desc
  desc(home => home.optionalProperty != null), // checks for both null and undefined
  asc(home => home.optionalProperty),
  // ...
))

因为用localeCompare()比较字符串是一件很常见的事情,所以可以将其作为asc()的一部分。

function hasMethod(item, methodName) {
  return item != null && typeof item[methodName] === "function";
}

function asc(fn) {
  return function (a, b) {
    a = fn(a);
    b = fn(b);

    const areLocaleComparable =
      hasMethod(a, "localeCompare") && hasMethod(b, "localeCompare");

    if (areLocaleComparable) return a.localeCompare(b);

    return -(a < b) || +(a > b);
  };
}