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Radashi

castComparator

Cast a value into a comparator function

230 bytes

Usage

Create a comparator function which can be passed into Array.prototype.sort. It accepts either a property name or a mapping function. Optionally, you can pass a custom compare function (e.g. for localeCompare use cases).

The first argument of castComparator is called the mapping. This can be either:

  • Function: If mapping is a function, it maps the input values to a comparable value.
  • Property Name: If mapping is a property name, it maps the input values to a property of the input values with a comparable value.
import * as 
import _
_ from 'radashi'


const 
const users: {
    id: number;
    firstName: string;
    lastName: string;
}[]
users = [
  { 
id: number
id: 1, 
firstName: string
firstName: 'Alice', 
lastName: string
lastName: 'Smith' },
  { 
id: number
id: 3, 
firstName: string
firstName: 'Charlie', 
lastName: string
lastName: 'Brown' },
  { 
id: number
id: 2, 
firstName: string
firstName: 'Drew', 
lastName: string
lastName: 'Johnson' },
]


const 
const compareById: _.Comparator<{
    id: _.Comparable;
}>
compareById = 
import _
_.
castComparator<"id">(mapping: "id", compare?: null | undefined, reverse?: boolean): _.Comparator<{
    id: _.Comparable;
}> (+4 overloads)
export castComparator
Cast a value into a comparator function.


    

  • Function: If mapping is a function, it maps the input
values to a comparable value.
    • 

  • Property Name: If mapping is a property name, it maps the
input values to a property of the input values with a comparable
value.
    • 



Optionally, you can pass a custom compare function that receives
the mapped values and returns a number. If not provided, values are
compared with the < and > built-in operators. A positive number
means the “right value” is greater than the “left value”, a
negative number means the “left value” is greater than the “right
value”, and 0 means both values are equal.
@see ― https://radashi.js.org/reference/function/castComparator
@example 
const compareUserNames = castComparator(
  (user) => user.name,
  (a, b) => b.localeCompare(a),
)


const users = [
  { name: 'John', age: 20 },
  { name: 'Jane', age: 25 },
  { name: 'Doe', age: 22 },
]


users.sort(compareUserNames)
// => [Doe, Jane, John]
@version ― 12.2.0
castComparator('id')
const users: {
    id: number;
    firstName: string;
    lastName: string;
}[]
users.
Array<{ id: number; firstName: string; lastName: string; }>.sort(compareFn?: ((a: {
    id: number;
    firstName: string;
    lastName: string;
}, b: {
    id: number;
    firstName: string;
    lastName: string;
}) => number) | undefined): {
    id: number;
    firstName: string;
    lastName: string;
}[]
Sorts an array in place.
This method mutates the array and returns a reference to the same array.
@param ― 
compareFn Function used to determine the order of the elements. It is expected to return
a negative value if the first argument is less than the second argument, zero if they're equal, and a positive
value otherwise. If omitted, the elements are sorted in ascending, ASCII character order.


[11,2,22,1].sort((a, b) => a - b)
sort(
const compareById: _.Comparator<{
    id: _.Comparable;
}>
compareById)
// [Alice, Drew, Charlie]


const 
const compareByFullName: _.Comparator<{
    id: number;
    firstName: string;
    lastName: string;
}>
compareByFullName = 
import _
_.
castComparator<unknown, (user: (typeof users)[number]) => string>(mapping: (user: (typeof users)[number]) => string, compare: _.Comparator<unknown>, reverse?: boolean): _.Comparator<{
    id: number;
    firstName: string;
    lastName: string;
}> (+4 overloads)
export castComparator
Cast a value into a comparator function.


    

  • Function: If mapping is a function, it maps the input
values to a comparable value.
    • 

  • Property Name: If mapping is a property name, it maps the
input values to a property of the input values with a comparable
value.
    • 



Optionally, you can pass a custom compare function that receives
the mapped values and returns a number. If not provided, values are
compared with the < and > built-in operators. A positive number
means the “right value” is greater than the “left value”, a
negative number means the “left value” is greater than the “right
value”, and 0 means both values are equal.
@see ― https://radashi.js.org/reference/function/castComparator
@example 
const compareUserNames = castComparator(
  (user) => user.name,
  (a, b) => b.localeCompare(a),
)


const users = [
  { name: 'John', age: 20 },
  { name: 'Jane', age: 25 },
  { name: 'Doe', age: 22 },
]


users.sort(compareUserNames)
// => [Doe, Jane, John]
@version ― 12.2.0
castComparator(
  (
user: {
    id: number;
    firstName: string;
    lastName: string;
}
user: typeof 
const users: {
    id: number;
    firstName: string;
    lastName: string;
}[]
users[number]) => `${
user: {
    id: number;
    firstName: string;
    lastName: string;
}
user.
firstName: string
firstName} ${
user: {
    id: number;
    firstName: string;
    lastName: string;
}
user.
lastName: string
lastName}`,
  (
a: unknown
a, 
b: unknown
b) => 
b: unknown
b.
any
localeCompare(
a: unknown
a),
)
const users: {
    id: number;
    firstName: string;
    lastName: string;
}[]
users.
Array<{ id: number; firstName: string; lastName: string; }>.sort(compareFn?: ((a: {
    id: number;
    firstName: string;
    lastName: string;
}, b: {
    id: number;
    firstName: string;
    lastName: string;
}) => number) | undefined): {
    id: number;
    firstName: string;
    lastName: string;
}[]
Sorts an array in place.
This method mutates the array and returns a reference to the same array.
@param ― 
compareFn Function used to determine the order of the elements. It is expected to return
a negative value if the first argument is less than the second argument, zero if they're equal, and a positive
value otherwise. If omitted, the elements are sorted in ascending, ASCII character order.


[11,2,22,1].sort((a, b) => a - b)
sort(
const compareByFullName: _.Comparator<{
    id: number;
    firstName: string;
    lastName: string;
}>
compareByFullName)
// [Alice, Charlie, Drew]

Compare Function

Optionally, you can pass a custom compare function that receives the mapped values and returns a number. If not provided, values are compared with the < and > built-in operators.

A positive number means the “right value” is greater than the “left value”, a negative number means the “left value” is greater than the “right value”, and 0 means both values are equal.

import * as 
import _
_ from 'radashi'


const 
const users: {
    id: number;
    firstName: string;
    lastName: string;
}[]
users = [
  { 
id: number
id: 1, 
firstName: string
firstName: 'Alice', 
lastName: string
lastName: 'Smith' },
  { 
id: number
id: 3, 
firstName: string
firstName: 'Charlie', 
lastName: string
lastName: 'Brown' },
  { 
id: number
id: 2, 
firstName: string
firstName: 'Drew', 
lastName: string
lastName: 'Johnson' },
]


const 
const compareByFullName: _.Comparator<{
    id: number;
    firstName: string;
    lastName: string;
}>
compareByFullName = 
import _
_.
castComparator<unknown, (user: (typeof users)[number]) => string>(mapping: (user: (typeof users)[number]) => string, compare: _.Comparator<unknown>, reverse?: boolean): _.Comparator<{
    id: number;
    firstName: string;
    lastName: string;
}> (+4 overloads)
export castComparator
Cast a value into a comparator function.


    

  • Function: If mapping is a function, it maps the input
values to a comparable value.
    • 

  • Property Name: If mapping is a property name, it maps the
input values to a property of the input values with a comparable
value.
    • 



Optionally, you can pass a custom compare function that receives
the mapped values and returns a number. If not provided, values are
compared with the < and > built-in operators. A positive number
means the “right value” is greater than the “left value”, a
negative number means the “left value” is greater than the “right
value”, and 0 means both values are equal.
@see ― https://radashi.js.org/reference/function/castComparator
@example 
const compareUserNames = castComparator(
  (user) => user.name,
  (a, b) => b.localeCompare(a),
)


const users = [
  { name: 'John', age: 20 },
  { name: 'Jane', age: 25 },
  { name: 'Doe', age: 22 },
]


users.sort(compareUserNames)
// => [Doe, Jane, John]
@version ― 12.2.0
castComparator(
  (
user: {
    id: number;
    firstName: string;
    lastName: string;
}
user: typeof 
const users: {
    id: number;
    firstName: string;
    lastName: string;
}[]
users[number]) => `${
user: {
    id: number;
    firstName: string;
    lastName: string;
}
user.
firstName: string
firstName} ${
user: {
    id: number;
    firstName: string;
    lastName: string;
}
user.
lastName: string
lastName}`,
  (
a: unknown
a, 
b: unknown
b) => 
b: unknown
b.
any
localeCompare(
a: unknown
a),
)


const users: {
    id: number;
    firstName: string;
    lastName: string;
}[]
users.
Array<{ id: number; firstName: string; lastName: string; }>.sort(compareFn?: ((a: {
    id: number;
    firstName: string;
    lastName: string;
}, b: {
    id: number;
    firstName: string;
    lastName: string;
}) => number) | undefined): {
    id: number;
    firstName: string;
    lastName: string;
}[]
Sorts an array in place.
This method mutates the array and returns a reference to the same array.
@param ― 
compareFn Function used to determine the order of the elements. It is expected to return
a negative value if the first argument is less than the second argument, zero if they're equal, and a positive
value otherwise. If omitted, the elements are sorted in ascending, ASCII character order.


[11,2,22,1].sort((a, b) => a - b)
sort(
const compareByFullName: _.Comparator<{
    id: number;
    firstName: string;
    lastName: string;
}>
compareByFullName)
// [Alice, Charlie, Drew]