cronr
v2.2.1
Published
Time-based job scheduler
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123
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ryuyutyoReadme
cronr · 
Inspired from unix cron, cronr is served as an time-based job scheduler which runs on browser and Node.js. It follows the basic standard macro pattern and makes somehow enhancement.
Feature
- More time control support, even to
millisecond - Works on browser and
Node.js - By default, jobs control support five available actions :
start,stop,stop,resumeandclear. - Standalone module to help calculate
nextTickonly, which provide aIteratorobject to fetch. - Add
webWorkerssupport, to avoid theonmessagehandle trigger delay due to the nature of Javascript's single thread.
Online demo
Cronr stroies -- online samples
Installation
- use
npmto install
npm install cronr- or use
yarnwith
yarn add cronrRunning on browser
- Downloading the
Cronr.umd.min.js(for time job scheduler)orCronrCounter.umd.min.js(to fetch the nextTick only)from './lib/minified'; - Add an
<script>tag which includes thebundlefile on your page - Refer to Cronr or CronrCounter for usage detail
Cronr
Job scheduler, which support cron macro pattern and has lots of handful methods.
- Cronr(pattern: string, callback: function, opts: obj)
| Property | Description | Type | Required|
| -------- | --- -------- | ---- | --- |
| pattern | cron macro format string | string | yes|
| callback | Function will be triggerd when time hit nextTick | function | yes|
opts has following available parameters
| Property | Description | Type | Required| Default |
| -------- | ----------- | ---- | --- | ---- |
| startTime | Starting point, when to start calculate the nextTick | Date | false | new Date() |
| endTime | Ending point, the schedulerd jobs will be canceled after this time | Date | false | none |
| immediate | When to trigger callback immediately when you start the job | boolean | false | false |
methods
| Method | Description | Signature |
| ------ | ----------- | ---- |
| start | Start the initial job | (): void => {} |
| stop | Suspend the running job | (): void => {} |
| resume | Resume the suspend job | (): void => {} |
| clear | Clear the job | (): void => {} |
| restart | Restart the register job | (): void => {} |
However, every method invoke has an order restriction.
startonly could be followed bystopandclearmethod.
| Method | Followed By |
| ------ | ----------- |
| start | ["stop", "clear"] |
| stop | ["resume", "clear"] |
| clear | ["restart"] |
Basic Usage
import Cronr from 'cronr';
// trigger on every second, 10, 20, 30, 40, 50, 00
const pattern = '*/10 * * * * *';
let count = 1;
const cb = () => count++;
const job = new Cronr(pattern, cb, {
startTime: new Date(2018, 3, 23, 10, 23, 36),
});
job.start();CronrCounter
It mainly consists of :
- Parsing
cronmacro pattern - A
Iteratorproperty which to provide thenextTickvalue.
- CronrCounter(opts: obj)
opts has the following avaible properties.
| Property | Description | Type | Required| Default |
| -------- | ----------- | ---- | --- | --- |
| name | Module name | string | false | undefined |
| pattern | cron macro pattern | string | true | -- |
| ts | Time Starting point, which means all the nextTick is calculated based on this value | Date | false | new Date()|
- Basic Usage
import CronrCounter from 'cronr/CronrCounter';
const counter = new CronrCounter({
name: 'testing',
pattern: '2,5 * * 3-12 3 *',
ts: new Date(2018, 7, 22, 10, 23, 16),
});
const data = counter.result;
const result = data.next().value; // '3/3/2019, 12:00:02 AM'
const result2 = data.next().value; // '3/3/2019, 12:00:05 AM'CronrWorker
This is an experimental feature which is integrated with webWorkers. It coulb be considered as an alternate of Crorn module。
Why using webWorkers
let i = 1;
const fn = (ts) => {
const id = setTimeout(() => {
const executedAt = new Date();
const diff = executedAt - ts;
window.clearTimeout(id);
console.log('executedAt ', executedAt, diff);
if (i < 10) {
fn(ts);
}
i++;
}, 500)
}
// result
// executedAt Mon May 07 2018 00:33:38 GMT+0800 (CST) 502
// executedAt Mon May 07 2018 00:33:38 GMT+0800 (CST) 1007
// executedAt Mon May 07 2018 00:33:39 GMT+0800 (CST) 1509
// executedAt Mon May 07 2018 00:33:39 GMT+0800 (CST) 2015
// executedAt Mon May 07 2018 00:33:40 GMT+0800 (CST) 2521
// executedAt Mon May 07 2018 00:33:40 GMT+0800 (CST) 3027
// executedAt Mon May 07 2018 00:33:41 GMT+0800 (CST) 3529
// executedAt Mon May 07 2018 00:33:41 GMT+0800 (CST) 4037
// executedAt Mon May 07 2018 00:33:42 GMT+0800 (CST) 4538
// executedAt Mon May 07 2018 00:33:42 GMT+0800 (CST) 5040
// executedAt Mon May 07 2018 00:33:43 GMT+0800 (CST) 5546
// executedAt Mon May 07 2018 00:33:43 GMT+0800 (CST) 6052
// executedAt Mon May 07 2018 00:33:44 GMT+0800 (CST) 6555
// executedAt Mon May 07 2018 00:33:44 GMT+0800 (CST) 7059
// executedAt Mon May 07 2018 00:33:45 GMT+0800 (CST) 7564
// executedAt Mon May 07 2018 00:33:45 GMT+0800 (CST) 8068
// executedAt Mon May 07 2018 00:33:46 GMT+0800 (CST) 8573
// executedAt Mon May 07 2018 00:33:46 GMT+0800 (CST) 9080
// executedAt Mon May 07 2018 00:33:47 GMT+0800 (CST) 9586
// executedAt Mon May 07 2018 00:33:47 GMT+0800 (CST) 10092According to the running result, As the counter become bigger, the delay will become much bigger. For example, if count === 10, the delay is only 40ms, but when the count is 20, it become 92. It is due to the nature of Javascript's single thread, setTimeout jobs could not running on concurrency. instead, they could be blockded if the main thread is busy on other things.
webWorkers provide a method to do a single job in a seperate thread. This job will not be affected by main thread's blocking. Then it also has a hand-on method postMessage to communiate with main thread.
-CronrWorker(pattern: string)
| Property | Description | Type | Required|
| -------- | ----------- | ---- | --- |
| pattern | cron macro format string | string | yes|
Basic CronrWorker Usage
import CronrWorker from 'cronr/CronrWorker'
const worker = CronrWorker(pattern);
worker.onmessage = (e) => {
const data = e.data;
const { nextTick, triggerAt, hit, status, action } = data;
if (action === 'trigger') {
this.store.set(hit, {
triggerAt,
nextTick,
});
this.setState({
count: this.state.count + 1,
status,
});
}
if (action === 'updateStatus') {
this.setState({
status,
});
}
};
worker.onerror = (e) => {
const { message } = e;
console.log(e.message);
};Cronr Macro Pattern
It mainly inspired from Cron - Wikipedia. Comparing with original format, it follows the basic syntax; For example, Every pattern is seperated by space; It still support special meaning characters(-, , and * etc);
However, it has addtional enhancement. Recently, it support time format till milliseconds. Just as follows showing.
* * * * * * *
┬ ┬ ┬ ┬ ┬ ┬ ┬
| | | | | | |
| | | | | | |_________ day of week (0 - 6)
| | | | | |_____________ month (1 - 12)
| | | | |_________________ day of month (1 - 31)
| | | |_____________________ hour (0 - 23)
| | |_________________________ minute (0 - 59)
| |_____________________________ second (0 - 59, optional)
|_________________________________ milliSecond (0 - 999, optional)How to write an valid macro pattern
You must provide a string which combines with at least 5 valid macro token(* or 1,2,4-5 will be considered as a token); It means if the token length is less than 7, it will has an auto-completion on the heading position.
const patten = '* * 5 * * * *' // retain the same
const pattern = '5 * * * *'; // => '* * 5 * * * *'
const pattern2 = '5 * * * * *'; // => '* 5 * * * * *'Simple macro samples
- Pay attention to the token length
'* * * * * * *' // running on every millisecond
'*/10 * * * * *' // running on every 10 seconds
'30 4 1,15 * 5' // run at 4:30 am on the 1st and 15th of each month, plus every Friday
'15 14 1 * *' // run at 2:15pm on the first of every month
'5 4 * * sun' // run at 5 after 4 every sundayif both "day of month" and "day of week" are restricted (not "*"), then one or both must match the current day.
Todo
Nonstandard predefined scheduling definitions
To support preset macro pattern, such as @yearly which means run once a year at midnight of 1 Jan.