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。
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,
}
]));
哇,这里有一些复杂的解。如此复杂,我决定想出一些更简单但也相当强大的东西。在这里;
function sortByPriority(data, priorities) {
if (priorities.length == 0) {
return data;
}
const nextPriority = priorities[0];
const remainingPriorities = priorities.slice(1);
const matched = data.filter(item => item.hasOwnProperty(nextPriority));
const remainingData = data.filter(item => !item.hasOwnProperty(nextPriority));
return sortByPriority(matched, remainingPriorities)
.sort((a, b) => (a[nextPriority] > b[nextPriority]) ? 1 : -1)
.concat(sortByPriority(remainingData, remainingPriorities));
}
这里有一个如何使用它的例子。
const data = [
{ id: 1, mediumPriority: 'bbb', lowestPriority: 'ggg' },
{ id: 2, highestPriority: 'bbb', mediumPriority: 'ccc', lowestPriority: 'ggg' },
{ id: 3, mediumPriority: 'aaa', lowestPriority: 'ggg' },
];
const priorities = [
'highestPriority',
'mediumPriority',
'lowestPriority'
];
const sorted = sortByPriority(data, priorities);
这将首先根据属性的优先级排序,然后根据属性的值进行排序。
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))
以下是我的简历,请参考,并举例说明:
function msort(arr, ...compFns) {
let fn = compFns[0];
arr = [].concat(arr);
let arr1 = [];
while (arr.length > 0) {
let arr2 = arr.splice(0, 1);
for (let i = arr.length; i > 0;) {
if (fn(arr2[0], arr[--i]) === 0) {
arr2 = arr2.concat(arr.splice(i, 1));
}
}
arr1.push(arr2);
}
arr1.sort(function (a, b) {
return fn(a[0], b[0]);
});
compFns = compFns.slice(1);
let res = [];
arr1.map(a1 => {
if (compFns.length > 0) a1 = msort(a1, ...compFns);
a1.map(a2 => res.push(a2));
});
return res;
}
let tstArr = [{ id: 1, sex: 'o' }, { id: 2, sex: 'm' }, { id: 3, sex: 'm' }, { id: 4, sex: 'f' }, { id: 5, sex: 'm' }, { id: 6, sex: 'o' }, { id: 7, sex: 'f' }];
function tstFn1(a, b) {
if (a.sex > b.sex) return 1;
else if (a.sex < b.sex) return -1;
return 0;
}
function tstFn2(a, b) {
if (a.id > b.id) return -1;
else if (a.id < b.id) return 1;
return 0;
}
console.log(JSON.stringify(msort(tstArr, tstFn1, tstFn2)));
//output:
//[{"id":7,"sex":"f"},{"id":4,"sex":"f"},{"id":5,"sex":"m"},{"id":3,"sex":"m"},{"id":2,"sex":"m"},{"id":6,"sex":"o"},{"id":1,"sex":"o"}]