Date overview
Various functions to aid in working with JavaScript’s Date object.
Added in v0.1.0
Table of contents
0 Types
Milliseconds (type alias)
Newtype representing milliseconds.
Signature
export type Milliseconds = Newtype<MillisecondsSymbol, number>
type Milliseconds = Newtype MillisecondsSymbol number
Example
import { Milliseconds, mkMilliseconds } from 'fp-ts-std/Date'
const second: Milliseconds = mkMilliseconds(1000)
Added in v0.7.0
1 Typeclass Instances
fieldMilliseconds
Field instance for Milliseconds, enabling arithmetic over the type.
Signature
export declare const fieldMilliseconds: Field<Milliseconds>
fieldMilliseconds :: Field Milliseconds
Example
import { fieldMilliseconds, mkMilliseconds } from 'fp-ts-std/Date'
assert.strictEqual(fieldMilliseconds.add(mkMilliseconds(2), mkMilliseconds(3)), mkMilliseconds(5))
Added in v0.7.0
isoMilliseconds
Iso instance for Milliseconds, enabling the use of lenses over the newtype pertaining to its isomorphic nature.
Signature
export declare const isoMilliseconds: Iso<Milliseconds, number>
isoMilliseconds :: Iso Milliseconds number
Example
import { isoMilliseconds, mkMilliseconds } from 'fp-ts-std/Date'
import { add } from 'fp-ts-std/Number'
assert.strictEqual(isoMilliseconds.modify(add(3))(mkMilliseconds(2)), mkMilliseconds(5))
Added in v0.7.0
ordMilliseconds
Ord instance for Milliseconds, enabling comparison between different instances of the type.
Signature
export declare const ordMilliseconds: Ord<Milliseconds>
ordMilliseconds :: Ord Milliseconds
Example
import { ordMilliseconds, mkMilliseconds } from 'fp-ts-std/Date'
import { LT } from 'fp-ts-std/Ordering'
assert.strictEqual(ordMilliseconds.compare(mkMilliseconds(0), mkMilliseconds(1)), LT)
Added in v0.7.0
3 Functions
fromMilliseconds
Get a Date from Milliseconds.
Signature
export declare const fromMilliseconds: (x: Milliseconds) => Date
fromMilliseconds :: Milliseconds -> Date
Example
import { fromMilliseconds, mkMilliseconds } from 'fp-ts-std/Date'
assert.deepStrictEqual(fromMilliseconds(mkMilliseconds(123)), new Date(123))
Added in v0.7.0
getTime
Get the time in milliseconds from a Date.
Signature
export declare const getTime: (x: Date) => Milliseconds
getTime :: Date -> Milliseconds
Example
import { getTime } from 'fp-ts-std/Date'
const d = new Date()
assert.strictEqual(getTime(d), d.getTime())
Added in v0.1.0
isDate
Check if a foreign value is a Date.
Signature
export declare const isDate: Refinement<unknown, Date>
isDate :: Refinement unknown Date
Example
import { isDate } from 'fp-ts-std/Date'
assert.strictEqual(isDate(new Date()), true)
assert.strictEqual(isDate({ not: { a: 'date' } }), false)
Added in v0.1.0
isValid
Check if a Date is actually valid. (We all love JavaScript, don’t we?)
Signature
export declare const isValid: Predicate<Date>
isValid :: Predicate Date
Example
import { isValid } from 'fp-ts-std/Date'
const valid = new Date()
const invalid = new Date('this will not parse')
assert.strictEqual(isValid(valid), true)
assert.strictEqual(isValid(invalid), false)
Added in v0.1.0
mkMilliseconds
Lift a number to the Milliseconds newtype.
Signature
export declare const mkMilliseconds: (n: number) => Milliseconds
mkMilliseconds :: number -> Milliseconds
Example
import { mkMilliseconds } from 'fp-ts-std/Date'
const second = mkMilliseconds(1000)
Added in v0.7.0
now
Get the time since the Unix Epoch in Milliseconds from a Date.
Signature
export declare const now: IO<Milliseconds>
now :: IO Milliseconds
Example
import { now, mkMilliseconds } from 'fp-ts-std/Date'
const x1970 = mkMilliseconds(0)
const x2065 = mkMilliseconds(3000000000000)
assert.strictEqual(now() > x1970, true)
assert.strictEqual(now() < x2065, true)
Added in v0.7.0
parseDate
Safely parse a date.
Signature
export declare const parseDate: (ts: string | number) => Option<Date>
parseDate :: string | number -> Option Date
Example
import { parseDate } from 'fp-ts-std/Date'
import * as O from 'fp-ts/Option'
const valid = 0
const invalid = 'this will not parse'
assert.deepStrictEqual(parseDate(valid), O.some(new Date(valid)))
assert.deepStrictEqual(parseDate(invalid), O.none)
Added in v0.1.0
toISOString
Returns a date as a string value in ISO format.
Signature
export declare const toISOString: (x: Date) => string
toISOString :: Date -> string
Example
import { toISOString } from 'fp-ts-std/Date'
const d = new Date()
assert.strictEqual(toISOString(d), d.toISOString())
Added in v0.1.0
toUTCString
Returns a date converted to a string using Universal Coordinated Time (UTC).
Signature
export declare const toUTCString: (x: Date) => string
toUTCString :: Date -> string
Example
import { toUTCString } from 'fp-ts-std/Date'
const d = new Date()
assert.strictEqual(toUTCString(d), d.toUTCString())
Added in v0.14.0
unMilliseconds
Unwrap a Milliseconds newtype back to its underlying number representation.
Signature
export declare const unMilliseconds: (ms: Milliseconds) => number
unMilliseconds :: Milliseconds -> number
Example
import { flow } from 'fp-ts/function'
import { Endomorphism } from 'fp-ts/Endomorphism'
import { mkMilliseconds, unMilliseconds } from 'fp-ts-std/Date'
const redundant: Endomorphism<number> = flow(mkMilliseconds, unMilliseconds)
Added in v0.7.0
unsafeParseDate
Parse a date, leaving open the risk of a failure to parse resulting in an invalid Date being returned.
Signature
export declare const unsafeParseDate: (x: string | number) => Date
unsafeParseDate :: string | number -> Date
Example
import { unsafeParseDate } from 'fp-ts-std/Date'
const valid = 0
const invalid = 'this will not parse'
assert.strictEqual(unsafeParseDate(valid).getTime(), 0)
assert.strictEqual(unsafeParseDate(invalid).getTime(), NaN)
Added in v0.1.0