cron-validate is a cron-expression validator written in TypeScript.
npm install cron-validate
!npm
Cron-validate is a cron-expression validator written in TypeScript.
The validation options are customizable and cron fields like seconds and years are supported.
Package is available on npm:
npm install -S cron-validate
``typescript
import cron from 'cron-validate'
const cronResult = cron(' *')
if (cronResult.isValid()) {
// !cronResult.isError()
// valid code
} else {
// error code
}
`
The cron function returns a Result-type, which is either Valid or Err.
For checking the returned result, just use result.isValid() or result.isError()
Both result types contain values:
`typescript
import cron from 'cron-validate'
const cronResult = cron(' *')
if (cronResult.isValid()) {
const validValue = cronResult.getValue()
// The valid value is a object containing all cron fields
console.log(validValue)
// In this case, it would be:
// { seconds: undefined, minutes: '', hours: '', daysOfMonth: '', months: '', daysOfWeek: '*', years: undefiend }
} else {
const errorValue = cronResult.getError()
// The error value contains an array of strings, which represent the cron validation errors.
console.log(errorValue) // string[] of error messages
}
`
Make sure to test the result type beforehand, because getValue() only works on Valid and getError() only works on Err. If you don't check, it will throw an error.
For further information, you can check out https://github.com/gDelgado14/neverthrow, because I used and modified his code for this package.
(Therefor not every documented function on his package is available on this package.)
To configure the validator, cron-validate uses a preset system. There are already defined presets (default, npm-node-cron or aws), but you can also define your own preset to use for your system. You can also use the override property to set certain option on single cron validates.
The following presets are already defined by cron-validate:
- default (see: http://crontab.org/)
- npm-node-cron (see: https://github.com/kelektiv/node-cron)
- aws-cloud-watch (see: https://docs.aws.amazon.com/de_de/AmazonCloudWatch/latest/events/ScheduledEvents.html)
- npm-cron-schedule (see: https://github.com/P4sca1/cron-schedule)
To select a preset for your validation, you can simply do this:
`typescript`
cron(' *', {
preset: 'npm-cron-schedule',
})
#### Defining and using your own preset
To define your own preset, use this:
`typescript`
registerOptionPreset('YOUR-PRESET-ID', {
presetId: 'YOUR-PRESET-ID',
useSeconds: false,
useYears: false,
useAliases: false, // optional, default to false
useBlankDay: false,
allowOnlyOneBlankDayField: false,
allowStepping: true, // optional, defaults to true
mustHaveBlankDayField: false, // optional, default to false
useLastDayOfMonth: false, // optional, default to false
useLastDayOfWeek: false, // optional, default to false
useNearestWeekday: false, // optional, default to false
useNthWeekdayOfMonth: false, // optional, default to false
seconds: {
minValue: 0,
maxValue: 59,
lowerLimit: 0, // optional, default to minValue
upperLimit: 59, // optional, default to maxValue
},
minutes: {
minValue: 0,
maxValue: 59,
lowerLimit: 0, // optional, default to minValue
upperLimit: 59, // optional, default to maxValue
},
hours: {
minValue: 0,
maxValue: 23,
lowerLimit: 0, // optional, default to minValue
upperLimit: 23, // optional, default to maxValue
},
daysOfMonth: {
minValue: 1,
maxValue: 31,
lowerLimit: 1, // optional, default to minValue
upperLimit: 31, // optional, default to maxValue
},
months: {
minValue: 0,
maxValue: 12,
lowerLimit: 0, // optional, default to minValue
upperLimit: 12, // optional, default to maxValue
},
daysOfWeek: {
minValue: 1,
maxValue: 7,
lowerLimit: 1, // optional, default to minValue
upperLimit: 7, // optional, default to maxValue
},
years: {
minValue: 1970,
maxValue: 2099,
lowerLimit: 1970, // optional, default to minValue
upperLimit: 2099, // optional, default to maxValue
},
})
The preset properties explained:
- presetId: string
- same id as in first function parameter
-
- enables seconds field in cron expression
-
- enables years field in cron expression
-
- enables aliases for month and daysOfWeek fields (ignores limits for month and daysOfWeek, so be aware of that)
-
- enables blank day notation '?' in daysOfMonth and daysOfWeek field
-
- requires a day field to not be blank (so not both day fields can be blank)
-
- optional, will default to true
- when set to false, disallows the use of the '/' operation for valid expressions
-
- requires a day field to be blank (so not both day fields are specified)
- when mixed with , it means that there will always be either day or day of week as ?
-
- enables the 'L' character to specify the last day of the month.
- accept negative offset after the 'L' for nth last day of the month.
- e.g.: would me the 2nd to last day of the month.useLastDayOfWeek: boolean
-
- enables the 'L' character to specify the last occurrence of a weekday in a month.
- e.g.: would mean the last friday of the month.useNearestWeekday: boolean
-
- enables the 'W' character to specify the use of the closest weekday.
- e.g.: would mean the weekday (mon-fri) closest to the 15th when the 15th is on sat-sun.useNthWeekdayOfMonth: boolean
-
- enables the '#' character to specify the Nth weekday of the month.
- e.g.: would mean the 3rd friday of the month (assuming 6 = friday).
* in cron fields (like seconds, minutes etc.):
- minValue: number
- minimum value of your cron interpreter (like npm-node-cron only supports 0-6 for weekdays)
- can't be set as override
-
- minimum value of your cron interpreter (like npm-node-cron only supports 0-6 for weekdays)
- can't be set as override
-
- lower limit for validation
- equal or greater than minValue
- if not set, default to minValue
-
- upper limit for validation
- equal or lower than maxValue
- if not set, defaults to maxValue
If you want to override a option for single cron validations, you can use the override property:
`typescript
console.log(cron(' ', {
preset: 'default', // second field not supported in default preset
override: {
useSeconds: true // override preset option
}
}))
console.log(cron(' 10-20 *', {
preset: 'default',
override: {
minutes: {
lowerLimit: 10, // override preset option
upperLimit: 20 // override preset option
}
}
}))
`
`typescript
import cron from 'cron-validate'
console.log(cron(' *').isValid()) // true
console.log(cron(' *').isError()) // false
console.log(cron(' 2,3,4 ').isValid()) // true
console.log(cron('0 /2 /5 ').isValid()) // true
console.log(cron(' ', { override: { useSeconds: true } }).isValid()) // true
console.log(cron(' ', { override: { useYears: true } }).isValid()) // true
console.log(
cron('30 *', {
override: {
useSeconds: true,
seconds: {
lowerLimit: 20,
upperLimit: 40,
},
},
}).isValid()
) // true
console.log(
cron(' 3 ', {
override: {
hours: {
lowerLimit: 0,
upperLimit: 2,
},
},
}).isValid()
) // false
console.log(
cron(' ? ', {
override: {
useBlankDay: true,
},
}).isValid()
) // true
console.log(
cron(' ? * ?', {
override: {
useBlankDay: true,
allowOnlyOneBlankDayField: true,
},
}).isValid()
) // false
``
- [x] Basic cron validation.
- [x] Error messenges with information about invalid cron expression.
- [x] Seconds field support.
- [x] Years field support.
- [x] Option presets (classic cron, node-cron, etc.)
- [x] Blank '?' daysOfMonth/daysOfWeek support
- [x] Last day of month.
- [x] Last specific weekday of month. (e.g. last Tuesday)
- [x] Closest weekday to a specific day of the month.
- [x] Nth specific weekday of month. (e.g. 2nd Tuesday)
- [x] Cron alias support.