Accept dates in CronosTask constructor (Closes #4)

changelog.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## [1.4.0] - 07 Aug 2019
+### Added
+ - Support for providing a date, array of dates, or a custom date sequence to `new CronosTask()` instead of a `CronosExpression` object
+
 ## [1.3.0] - 30 Jul 2019
 ### Added
  - Support wrap-around ranges for cyclic type fields (ie. *Second*, *Minute*, *Hour*, *Month* and *Day of Week*)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "cronosjs",
-  "version": "1.3.0",
+  "version": "1.4.0",
   "description": "A cron based task scheduler for node and the browser, with extended syntax and timezone support.",
   "keywords": [
     "cron",

readme.md

@@ -67,6 +67,22 @@ task
     console.log(`No more dates matching expression`)
   })
   .start()
+
+// schedule tasks from a list of dates
+const taskFromDates = new CronosTask([
+  new Date(2020, 7, 23, 9, 45, 0),
+  1555847845000,
+  '5 Oct 2019 17:32',
+])
+
+taskFromDates
+  .on('run', (timestamp) => {
+    console.log(`Task triggered at ${timestamp}`)
+  })
+  .on('ended', () => {
+    console.log(`No more dates in list`)
+  })
+  .start()
 ```
 
 
@@ -283,10 +299,21 @@ import {
 ### CronosTask
 ```class CronosTask```
 
-#### Constructor
-```new CronosTask(expression)```
- - `expression: CronosExpression`  
-  An instance of [CronosExpression](#cronosexpression)
+#### Constructor (3 overloads)
+ - ```new CronosTask(sequence)```
+    - `sequence: DateSequence`  
+      Either an instance of [CronosExpression](#cronosexpression) or any other object that implements the `DateSequence` interface
+      ```typescript
+      interface DateSequence {
+        nextDate: (afterDate: Date) => Date | null
+      }
+      ```
+ - ```new CronosTask(date)```
+    - `date: Date | string | number`  
+      Either a `Date`, a timestamp, or a string repesenting a valid date, parsable by `new Date()`
+ - ```new CronosTask(dates)```
+    - `dates: (Date | string | number)[]`  
+      An array of dates accepted valid in above constructor
 
 #### Properties
  - `nextRun: Date | null` (readonly)  

src/expression.ts

@@ -1,11 +1,12 @@
 import { CronosDaysExpression, _parse } from './parser'
 import { CronosDate, CronosTimezone } from './date'
+import { DateSequence } from './scheduler'
 import { sortAsc } from './utils'
 
 const hourinms = 60 * 60 * 1000
 const findFirstFrom = (from: number, list: number[]) => list.findIndex(n => n >= from)
 
-export class CronosExpression {
+export class CronosExpression implements DateSequence {
   private timezone?: CronosTimezone
   private skipRepeatedHour = true
   private missingHour: 'insert' | 'offset' | 'skip' = 'insert'

src/scheduler.ts

@@ -1,5 +1,3 @@
-import { CronosExpression } from './expression'
-
 const maxTimeout = Math.pow(2, 31) - 1
 const scheduledTasks: CronosTask[] = []
 
@@ -46,13 +44,36 @@ function runScheduledTasks() {
   } else runningTimer = null
 }
 
+export interface DateSequence {
+  nextDate: (afterDate: Date) => Date | null
+}
+
+class DateArraySequence implements DateSequence {
+  private _dates: Date[]
+
+  constructor(dateLikes: DateLike[]) {
+    this._dates = dateLikes.map(dateLike => {
+      const date = new Date(dateLike)
+      if (isNaN(date.getTime())) throw new Error('Invalid date')
+      return date
+    }).sort((a, b) => a.getTime() - b.getTime())
+  }
+
+  nextDate(afterDate: Date) {
+    const nextIndex = this._dates.findIndex(d => d > afterDate)
+    return nextIndex === -1 ? null : this._dates[nextIndex]
+  }
+}
+
 type CronosTaskListeners = {
   'started': () => void
   'stopped': () => void
   'run':     (timestamp: number) => void
   'ended':   () => void
 }
 
+type DateLike = Date | string | number
+
 export class CronosTask {
   private _listeners: {
     [K in keyof CronosTaskListeners]: Set<CronosTaskListeners[K]>
@@ -63,12 +84,21 @@ export class CronosTask {
     'ended': new Set(),
   }
   private _timestamp?: number
-  private _expression: CronosExpression
+  private _sequence: DateSequence
 
+  constructor(sequence: DateSequence)
+  constructor(dates: DateLike[])
+  constructor(date: DateLike)
   constructor(
-    expression: CronosExpression,
+    sequenceOrDates: DateSequence | DateLike[] | DateLike,
   ) {
-    this._expression = expression
+    if (Array.isArray(sequenceOrDates)) this._sequence = new DateArraySequence(sequenceOrDates)
+    else if (
+      typeof sequenceOrDates === 'string' || 
+      typeof sequenceOrDates === 'number' ||
+      sequenceOrDates instanceof Date
+    ) this._sequence = new DateArraySequence([sequenceOrDates])
+    else this._sequence = sequenceOrDates
   }
 
   start() {
@@ -99,7 +129,7 @@ export class CronosTask {
   }
 
   private _updateTimestamp() {
-    const nextDate = this._expression.nextDate(
+    const nextDate = this._sequence.nextDate(
       this._timestamp ? new Date(this._timestamp) : new Date()
     )
 

tests/api.test.js

@@ -159,6 +159,42 @@ describe('Scheduling tests', () => {
     expect(task.isRunning).toEqual(false)
   })
 
+  test('CronosTask with array of dates', () => {
+    const startedCallback = jest.fn()
+    const runCallback = jest.fn()
+
+    const fromDate = '2019-04-21T11:23:45Z'
+    mockDate(fromDate)
+
+    const task = new CronosTask(
+      [new Date(2020, 7, 23, 9, 45, 0), 1555847845000, '5 Oct 2019 17:32']
+    )
+
+    task
+      .on('started', startedCallback)
+      .on('run', runCallback)
+
+    expect(startedCallback).not.toBeCalled()
+
+    task.start()
+
+    expect(startedCallback).toBeCalled()
+
+    mockDate('2019-04-21T11:57:25Z')
+    jest.runOnlyPendingTimers()
+
+    expect(runCallback).toHaveBeenCalledTimes(1)
+    expect(runCallback).toHaveBeenLastCalledWith( getTimestamp('2019-04-21T11:57:25Z') )
+
+    task.off('run', runCallback)
+  })
+
+  test('CronosTask with invalid date', () => {
+    expect(
+      () => new CronosTask('invalid')
+    ).toThrow()
+  })
+
 })
 
 describe('CronosExpression.cronString and .toString()', () => {