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cron-parser
Advanced tools
The cron-parser npm package is a utility for parsing crontab instructions. It allows users to interpret cron schedule expressions and calculate the next run times for jobs. It is useful for scheduling tasks in Node.js applications.
Parsing Cron Expressions
This feature allows users to parse a cron expression and get the next execution times. The code sample demonstrates how to parse a cron expression that runs every 2 minutes and log the next execution time.
const cronParser = require('cron-parser');
try {
const interval = cronParser.parseExpression('*/2 * * * *');
console.log('Date: ', interval.next().toString()); // Get the next date
} catch (err) {
console.error('Error: ' + err.message);
}
Iterating Over Execution Times
This feature allows users to iterate over the execution times of a cron job. The code sample demonstrates how to get the next 5 execution times for a cron expression that runs at the start of every hour.
const cronParser = require('cron-parser');
try {
const interval = cronParser.parseExpression('0 * * * *');
for (let i = 0; i < 5; i++) {
console.log('Date: ', interval.next().toString()); // Get the next 5 dates
}
} catch (err) {
console.error('Error: ' + err.message);
}
Handling Cron Expression with Timezone
This feature allows users to parse a cron expression with a specific timezone. The code sample demonstrates how to parse a cron expression that runs at the start of every hour, considering the timezone of Europe/Amsterdam.
const cronParser = require('cron-parser');
try {
const options = {
currentDate: new Date('Wed, 26 Dec 2012 14:38:53 GMT'),
tz: 'Europe/Amsterdam'
};
const interval = cronParser.parseExpression('0 * * * *', options);
console.log('Date: ', interval.next().toString()); // Get the next date considering timezone
} catch (err) {
console.error('Error: ' + err.message);
}
node-cron is a task scheduler in pure JavaScript for Node.js based on cron syntax. It allows you to schedule tasks to be executed at specific times or intervals. It is similar to cron-parser but also includes the ability to execute the jobs, not just parse cron expressions.
node-schedule is a flexible cron-like and not-cron-like job scheduler for Node.js. It allows for more complex scheduling than standard cron expressions, offering a higher level of customization. It is similar to cron-parser in parsing cron expressions but also provides an extensive job scheduling system.
bree is a job scheduler for Node.js with cron and human-friendly syntax. It supports cron expressions and allows for scheduling jobs with additional features like job timeouts and concurrency control. Bree is more feature-rich compared to cron-parser, which focuses solely on parsing cron expressions.
agenda is a light and flexible job scheduling library for Node.js. It uses MongoDB for job storage and offers features like job prioritization, concurrency, and repeating jobs. While cron-parser is focused on parsing cron expressions, agenda provides a full job scheduling system with persistence.
Node.js library for parsing crontab instructions. It includes support for timezones and DST transitions.
npm install cron-parser
* * * * * *
┬ ┬ ┬ ┬ ┬ ┬
│ │ │ │ │ |
│ │ │ │ │ └ day of week (0 - 7) (0 or 7 is Sun)
│ │ │ │ └───── month (1 - 12)
│ │ │ └────────── day of month (1 - 31)
│ │ └─────────────── hour (0 - 23)
│ └──────────────────── minute (0 - 59)
└───────────────────────── second (0 - 59, optional)
Supports mixed use of ranges and range increments (L and W characters are not supported currently). See tests for examples.
Simple expression.
var parser = require('cron-parser');
try {
var interval = parser.parseExpression('*/2 * * * *');
console.log('Date: ', interval.next().toString()); // Sat Dec 29 2012 00:42:00 GMT+0200 (EET)
console.log('Date: ', interval.next().toString()); // Sat Dec 29 2012 00:44:00 GMT+0200 (EET)
console.log('Date: ', interval.prev().toString()); // Sat Dec 29 2012 00:42:00 GMT+0200 (EET)
console.log('Date: ', interval.prev().toString()); // Sat Dec 29 2012 00:40:00 GMT+0200 (EET)
} catch (err) {
console.log('Error: ' + err.message);
}
Iteration with limited timespan. Also returns ES6 compatible iterator (when iterator flag is set to true).
var parser = require('cron-parser');
var options = {
currentDate: new Date('Wed, 26 Dec 2012 12:38:53 UTC'),
endDate: new Date('Wed, 26 Dec 2012 14:40:00 UTC'),
iterator: true
};
try {
var interval = parser.parseExpression('*/22 * * * *', options);
while (true) {
try {
var obj = interval.next();
console.log('value:', obj.value.toString(), 'done:', obj.done);
} catch (e) {
break;
}
}
// value: Wed Dec 26 2012 14:44:00 GMT+0200 (EET) done: false
// value: Wed Dec 26 2012 15:00:00 GMT+0200 (EET) done: false
// value: Wed Dec 26 2012 15:22:00 GMT+0200 (EET) done: false
// value: Wed Dec 26 2012 15:44:00 GMT+0200 (EET) done: false
// value: Wed Dec 26 2012 16:00:00 GMT+0200 (EET) done: false
// value: Wed Dec 26 2012 16:22:00 GMT+0200 (EET) done: true
} catch (err) {
console.log('Error: ' + err.message);
}
Timezone support
var parser = require('cron-parser');
var options = {
currentDate: '2016-03-27 00:00:01',
tz: 'Europe/Athens'
};
try {
var interval = parser.parseExpression('0 * * * *', options);
console.log('Date: ', interval.next().toString()); // Date: Sun Mar 27 2016 01:00:00 GMT+0200
console.log('Date: ', interval.next().toString()); // Date: Sun Mar 27 2016 02:00:00 GMT+0200
console.log('Date: ', interval.next().toString()); // Date: Sun Mar 27 2016 04:00:00 GMT+0300 (Notice DST transition)
} catch (err) {
console.log('Error: ' + err.message);
}
currentDate
and endDate
accept string
, integer
and Date
as input.
In case of using string
as input, not every string format accepted
by the Date
constructor will work correctly. The supported formats are: ISO8601
and the older
ASP.NET JSON Date
format. The reason being that those are the formats accepted by the
moment
library which is being used to handle dates.
Using Date
as an input can be problematic specially when using the tz
option. The issue being that, when creating a new Date
object without
any timezone information, it will be created in the timezone of the system that is running the code. This (most of times) won't be what the user
will be expecting. Using one of the supported string
formats will solve the issue(see timezone example).
utc
is enabledFAQs
Node.js library for parsing crontab instructions
The npm package cron-parser receives a total of 3,105,860 weekly downloads. As such, cron-parser popularity was classified as popular.
We found that cron-parser demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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