previous

Navigate to the previous period of the same type.

API Levels

This function is available in multiple API levels:

Level 1: Pure Function

import { period, previous } from '@allystudio/usetemporal/operations'
import { createNativeAdapter } from '@allystudio/usetemporal/native'

const adapter = createNativeAdapter()
const month = period(adapter, new Date(), 'month')
const lastMonth = previous(adapter, month)

Level 2: Builder Method

import { createTemporal } from '@allystudio/usetemporal'
import { createNativeAdapter } from '@allystudio/usetemporal/native'

const temporal = createTemporal({ adapter: createNativeAdapter() })
const month = temporal.period(new Date(), 'month')
const lastMonth = temporal.previous(month)

Signatures

// Level 1 (Pure Function)
function previous(adapter: Adapter, period: Period): Period

// Level 2 (Builder Method)
temporal.previous(period: Period): Period

Parameters

Level 1 (Pure Function)

• adapter - Adapter - The date adapter instance
• period - Period - The current period to navigate from

Level 2 (Builder Method)

• period - Period - The current period to navigate from

Returns

Period - The previous period of the same type and duration

Description

Creates a new period that immediately precedes the given period, maintaining the same unit type and duration. For custom periods, the duration is preserved.

Examples

Basic Usage (Level 1)

import { period, previous } from '@allystudio/usetemporal/operations'
import { createNativeAdapter } from '@allystudio/usetemporal/native'

const adapter = createNativeAdapter()

// Navigate to previous day
const today = period(adapter, new Date(), 'day')
const yesterday = previous(adapter, today)

// Navigate to previous month
const month = period(adapter, new Date(), 'month')
const lastMonth = previous(adapter, month)

// Navigate to previous year
const year = period(adapter, new Date(), 'year')
const lastYear = previous(adapter, year)

Builder API (Level 2)

import { createTemporal } from '@allystudio/usetemporal'
import { createNativeAdapter } from '@allystudio/usetemporal/native'

const temporal = createTemporal({ adapter: createNativeAdapter() })

const month = temporal.period(new Date(), 'month')
const lastMonth = temporal.previous(month)
const twoMonthsAgo = temporal.previous(lastMonth)

Custom Period Navigation

import { period, previous } from '@allystudio/usetemporal/operations'
import { createNativeAdapter } from '@allystudio/usetemporal/native'

const adapter = createNativeAdapter()

// Custom period (e.g., sprint)
const sprint = period(adapter, {
  start: new Date('2024-01-15'),
  end: new Date('2024-01-29') // 14 days
})

// Previous sprint (preserves duration)
const previousSprint = previous(adapter, sprint)
// { start: 2024-01-01, end: 2024-01-15, type: 'custom' }

Chaining Navigation

import { period, previous } from '@allystudio/usetemporal/operations'
import { createNativeAdapter } from '@allystudio/usetemporal/native'

const adapter = createNativeAdapter()

// Navigate multiple steps backward
const month = period(adapter, new Date(), 'month')
const twoMonthsAgo = previous(adapter, previous(adapter, month))

// Or use go() for better performance
import { go } from '@allystudio/usetemporal/operations'
const twoMonthsAgo2 = go(adapter, month, -2)

TypeScript

Full type safety:

import type { Adapter, Period } from '@allystudio/usetemporal'
import { period, previous } from '@allystudio/usetemporal/operations'
import { createNativeAdapter } from '@allystudio/usetemporal/native'

const adapter: Adapter = createNativeAdapter()
const month: Period = period(adapter, new Date(), 'month')
const lastMonth: Period = previous(adapter, month)

See Also

• next() - Navigate forward
• go() - Navigate multiple steps at once
• period() - Create periods
• Choosing API Level - Which level to use
• Level 1 API - Pure functions documentation
• Level 2 API - Builder pattern documentation