cron schedule下载 - cron schedule源代码下载

cron schedule

其他源码

v5.0.4

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克朗安排

Node.js，Deno和浏览器的零依赖性cron解析器和调度程序。在NPM和JSR上发布

特征

解析cron表达式。
从特定的开始日期获取下一个或以前的时间表。
检查日期是否与Cron表达式匹配。
根据CRON表达式安排函数调用。
支持node.js，deno和浏览器（仅ESM）
轻巧且摇摇欲坠。

安装和用法

node.js

通过NPM：

$ npm install cron-schedule

通过纱线：

$ yarn add cron-schedule

通过PNPM：

$ pnpm add cron-schedule

20.12 18.20 。其他版本的node.js也可能起作用，但这没有测试。

用法

 import { parseCronExpression } from 'cron-schedule'
const cron = parseCronExpression ( '*/5 * * * *' )
console . log ( cron . getNextDate ( new Date ( 2020 , 10 , 20 , 18 , 32 ) ) )
// 2020-11-20T17:35:00.000Z

通过CDN浏览器

 < script type =" module " >
  import { parseCronExpression } from 'https://cdn.skypack.dev/cron-schedule@:version'
  const cron = parseCronExpression ( '*/5 * * * *' )
  console . log ( cron . getNextDate ( new Date ( 2020 , 10 , 20 , 18 , 32 ) ) )
  // 2020-11-20T17:35:00.000Z
</ script >

上面的示例使用Skypack。

丹诺

 import { parseCronExpression } from 'npm:cron-schedule@:version'
const cron = parseCronExpression ( '*/5 * * * *' )
console . log ( cron . getNextDate ( new Date ( 2020 , 10 , 20 , 18 , 32 ) ) )
// 2020-11-20T17:35:00.000Z

另外，您可以使用deno add @p4sca1/cron-schedule ，并从@p4sca1/cron-schedule中导入，或从没有安装步骤的情况下从jsr:@p4sca1/cron-schedule 。

注释：版本占位符

DENO Import和Skypack CDN URL包含A :version占位符。替换:version 。支持SEMVER范围。始终使用最新的4.x版本使用^4.0.0 。有关可用版本的列表，请参见https://www.npmjs.com/package/package/cron-schedule。

使用Cron表达式

 // Import method to parse a cron expression.
import { parseCronExpression } from 'cron-schedule'

// Parse a cron expression to return a Cron instance.
const cron = parseCronExpression ( '*/5 * * * *' )

// Get the next date starting from the given start date or now.
cron . getNextDate ( startDate ?: Date ) : Date

// Get the specified amount of future dates starting from the given start date or now.
cron . getNextDates ( amount : number , startDate ?: Date ) : Date [ ]

// Get an ES6 compatible iterator which iterates over the next dates starting from startDate or now.
// The iterator runs until the optional endDate is reached or forever.
// The advantage of an iterator is that you can get more further dates on demand by using iterator.next().
cron . getNextDatesIterator ( startDate : Date = new Date ( ) , endDate ?: Date ) : Generator < Date , undefined , undefined >

// Get the previou date starting from the given start date or now.
cron . getPrevDate ( startDate : Date = new Date ( ) ) : Date

// Get the specified amount of previous dates starting from the given start date or now.
cron . getPrevDates ( amount : number , startDate ?: Date ) : Date [ ]

// Get an ES6 compatible iterator which iterates over the previous dates starting from startDate or now.
// The iterator runs until the optional endDate is reached or forever.
// The advantage of an iterator is that you can get more previous dates on demand by using iterator.next().
cron . getPrevDatesIterator ( startDate : Date = new Date ( ) , endDate ?: Date ) : Generator < Date , undefined , undefined >

// Check whether there is a cron date at the given date.
cron . matchDate ( date : Date ) : boolean

根据Cron表达式安排任务

您可以根据CRON表达式安排要执行的任务。 Cron-Schedule配备了2个不同的调度程序。

如果使用Typescript，请确保将compilerOptions.moduleResolution设置为node16或nodenext 。

1。基于计时器的调度程序

基于计时器的CRON调度程序为每个计划的CRON创建一个计时器。当节点超时限制超过约24天时，它会使用多个连续超时。

 // Import the scheduler.
import { TimerBasedCronScheduler as scheduler } from 'cron-schedule/schedulers/timer-based.js'

// Create a timeout, which fill fire the task on the next cron date.
// An optional errorHandler can be provided, which is called when the task throws an error or returns a promise that gets rejected.
// Returns a handle which can be used to clear the timeout using clearTimeoutOrInterval.
scheduler . setTimeout ( cron : Cron , task : ( ) = > unknown , opts ?: { errorHandler ?: ( err : Error ) = > unknown } ) : ITimerHandle

// Create an interval, which will fire the given task on every future cron date.
// This uses consecutive calls to scheduler.setTimeout under the hood.
// An optional errorHandler can be provided, which is called when the task throws an error or returns a promise that gets rejected.
// The task remains scheduled when an error occurs.
// Returns a handle which can be used to clear the timeout using clearTimeoutOrInterval.
scheduler . setInterval ( cron : Cron , task : ( ) = > unknown , opts ?: { errorHandler ?: ( err : Error ) = > unknown } ) : ITimerHandle

// Clear a timeout or interval, making sure that the task will no longer execute.
scheduler . clearTimeoutOrInterval ( handle : ITimerHandle ) : void

优点：

任务完全安排到下一个Cron日期的第二个。

缺点：

每个任务有一个计时器，如果您有许多计划的任务，则与基于间隔的调度程序相比，性能可能会导致性能较低。

2。基于间隔的调度程序

基于间隔的调度程序以固定的间隔检查适当任务。因此，分配给调度程序的所有任务只有一个间隔。您可以有多个基于间隔的调度程序的实例。

 // Import the scheduler.
import { IntervalBasedCronScheduler } from 'cron-schedule/schedulers/interval-based.js'

// Instantiate a new instance of the scheduler with the given interval. In this example, the scheduler would check every 60 seconds.
const scheduler = new IntervalBasedCronScheduler ( 60 * 1000 )

// Register a new task that will be executed on every future cron date, or only on the next cron date if isOneTimeTask is true.
// An optional errorHandler can be provided, which is called when the task throws an error or returns a promise that gets rejected.
// The task remains scheduled when an error occurs (if not a one time task). Tasks are at max executed only once per interval.
// Returns an id to be used with unregisterTask.
scheduler . registerTask ( cron : Cron , task : ( ) = > unknown , opts ?: { isOneTimeTask ?: boolean , errorHandler ?: ( err : Error ) = > unknown } ) : number

// Unregister a task causing it to no longer be executed.
scheduler . unregisterTask ( id : number ) : void

// You can stop the scheduler, which clears the interval.
scheduler . stop ( )

// You can start the scheduler after stopping it again. A newly created scheduler is started by default.
// Tasks that were due while the scheduler was stopped will be executed on the next interval tick (but only a single time).
scheduler . start ( )

优点：

所有任务只有一个间隔，这是相当性能的。

缺点：

任务在CRON日期不准确执行。
每个间隔只能执行任务一次。

对于大多数人来说，基于计时器的调度程序应该是一个不错的选择。但是，Settimeout对于长时间延迟可能是不可靠的。当您遇到长时间 /间隔因许多计划任务而遇到性能问题的问题时，您应该考虑基于间隔的调度程序。

cron表达格式

cron_schedule使用Linux cron语法，如下所述，您可以选择通过使用另一个字段来预定分钟字段来指定秒。

 ┌───────────── second (0 - 59, optional)
│ ┌───────────── minute (0 - 59)
│ │ ┌───────────── hour (0 - 23)
│ │ │ ┌───────────── day of month (1 - 31)
│ │ │ │ ┌───────────── month (1 - 12)
│ │ │ │ │ ┌───────────── weekday (0 - 7)
* * * * * *

支持所有Linux cron功能，包括