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July 10, 2023 10:21
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type SortableType = number | string | boolean; | |
type SortFn<T> = (el: T) => SortableType; | |
interface SortHelperApi<T> { | |
sortBy(fn: SortFn<T>, decrescent?: boolean): SortHelperApi<T>; | |
execute(): T[]; | |
} | |
/** | |
* helps sorting arrays | |
* accepts multiple calls to sortBy (1st takes precedence to 2nd, etc.) | |
* 2nd argument on sortBy is whether the sorting is in decreasing order | |
* one must call execute to get back the sorted array (without side-effects on original array) | |
*/ | |
export function sortHelper<T>(arr: T[]): SortHelperApi<T> { | |
const sortFns: SortFn<T>[] = []; | |
const sortDecs: boolean[] = []; | |
const api: SortHelperApi<T> = { | |
sortBy(fn: SortFn<T>, decrescent = false) { | |
sortFns.unshift(fn); | |
sortDecs.unshift(decrescent); | |
return api; | |
}, | |
execute(): T[] { | |
let finalArr = arr.slice(); | |
let i = 0; | |
for (const fn of sortFns) { | |
const dec: boolean = sortDecs[i++]; | |
const arr2: [T, SortableType][] = finalArr.map((el: T) => [el, fn(el)]); | |
arr2.sort((a_, b_) => { | |
const a = a_[1]; | |
const b = b_[1]; | |
if (dec) return a > b ? -1 : a < b ? 1 : 0; | |
return a > b ? 1 : a < b ? -1 : 0; | |
}); | |
finalArr = arr2.map((el) => el[0]); | |
} | |
return finalArr; | |
}, | |
}; | |
return api; | |
} | |
/* | |
// EXAMPLE USAGE FOLLOWS: | |
const people = [ | |
{ name: 'john', age: 12, gender: 'm' }, | |
{ name: 'mary', age: 6, gender: 'f' }, | |
{ name: 'mary', age: 21, gender: 'f' }, | |
{ name: 'josh', age: 33, gender: 'm' }, | |
]; | |
const people2 = sortHelper(people) | |
.sortBy((p) => p.gender) | |
.sortBy((p) => p.age, true) | |
.execute(); | |
console.log('people', people); | |
console.log('people2', people2); | |
*/ |
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