effect-io-ai

Package: effect
Module: DateTime

DateTime.mutate

Modifies a DateTime with a mutable local Date copy.

When to use

Use to adjust calendar fields in the DateTime’s own time zone with an existing Date mutation API.

Details

The Date will first have the time zone applied if possible, and then be converted back to a DateTime within the same time zone.

Supports disambiguation when the new wall clock time is ambiguous.

Example (Mutating DateTime values with Dates)

import { DateTime } from "effect"

const dt = DateTime.makeUnsafe("2024-01-01T12:00:00Z")

const modified = DateTime.mutate(dt, (date) => {
  date.setHours(15) // Set to 3 PM
  date.setMinutes(30) // Set to 30 minutes
})

console.log(DateTime.formatIso(modified)) // "2024-01-01T15:30:00.000Z"

Signature

declare const mutate: { (f: (date: Date) => void, options?: { readonly disambiguation?: Disambiguation | undefined; }): <A extends DateTime>(self: A) => A; <A extends DateTime>(self: A, f: (date: Date) => void, options?: { readonly disambiguation?: Disambiguation | undefined; }): A; }

Source

Since v3.6.0