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

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);
  };
}

其他回答

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。

这是一个通用的多维排序,允许在每个层次上进行反转和/或映射。

用Typescript编写。对于Javascript,请查看这个JSFiddle

的代码

type itemMap = (n: any) => any;

interface SortConfig<T> {
  key: keyof T;
  reverse?: boolean;
  map?: itemMap;
}

export function byObjectValues<T extends object>(keys: ((keyof T) | SortConfig<T>)[]): (a: T, b: T) => 0 | 1 | -1 {
  return function(a: T, b: T) {
    const firstKey: keyof T | SortConfig<T> = keys[0];
    const isSimple = typeof firstKey === 'string';
    const key: keyof T = isSimple ? (firstKey as keyof T) : (firstKey as SortConfig<T>).key;
    const reverse: boolean = isSimple ? false : !!(firstKey as SortConfig<T>).reverse;
    const map: itemMap | null = isSimple ? null : (firstKey as SortConfig<T>).map || null;

    const valA = map ? map(a[key]) : a[key];
    const valB = map ? map(b[key]) : b[key];
    if (valA === valB) {
      if (keys.length === 1) {
        return 0;
      }
      return byObjectValues<T>(keys.slice(1))(a, b);
    }
    if (reverse) {
      return valA > valB ? -1 : 1;
    }
    return valA > valB ? 1 : -1;
  };
}

用法示例

先按姓排序,再按名排序:

interface Person {
  firstName: string;
  lastName: string;
}

people.sort(byObjectValues<Person>(['lastName','firstName']));

按语言代码的名称排序,而不是按语言代码排序(见地图),然后按降序排序(见反向)。

interface Language {
  code: string;
  version: number;
}

// languageCodeToName(code) is defined elsewhere in code

languageCodes.sort(byObjectValues<Language>([
  {
    key: 'code',
    map(code:string) => languageCodeToName(code),
  },
  {
    key: 'version',
    reverse: true,
  }
]));

为了简化操作,可以使用这些辅助函数。

您可以根据需要对任意多个字段进行排序。对于每个排序字段,指定属性名,然后可选地指定-1作为排序方向,以降序排序而不是升序排序。

const data = [ {"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"}, {"h_id":"7","city":"New York","state":"NY","zip":"00010","price":"800500"} ] const sortLexically = (p,d=1)=>(a,b)=>d * a[p].localeCompare(b[p]) const sortNumerically = (p,d=1)=>(a,b)=>d * (a[p]-b[p]) const sortBy = sorts=>(a,b)=>sorts.reduce((r,s)=>r||s(a,b),0) // sort first by city, then by price descending data.sort(sortBy([sortLexically('city'), sortNumerically('price', -1)])) console.log(data)

今天我做了一个相当通用的多特征排序器。你可以在这里看看byjs: https://github.com/Teun/thenBy.js

它允许您使用标准数组。排序,但使用firstBy(). thenby (). thenby()样式。它比上面发布的解决方案少了很多代码和复杂性。

在这里,您可以尝试按多个字段进行排序的更小且方便的方法!

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" } ]; homes.sort((a, b)=> { if (a.city === b.city){ return a.price < b.price ? -1 : 1 } else { return a.city < b.city ? -1 : 1 } }) console.log(homes);