# OnSchedule

This allows you to trigger your task based on a predefined schedule, either a cron expression or an "every x" notation.The interface is as follows:

```javascript
engine.onSchedule(
    fn, // function to execute
    schedule, // cron expression / every x minutes/hours/days
    network, // string representation of one of the supported networks
    config // key:value object
)
```

### Cron Expression

Standard cron expression in UTC timezone.

[More on cron](https://en.wikipedia.org/wiki/Cron)

Cron expression utilizes the following format:

```
 *    *    *    *    *
┬    ┬    ┬    ┬    ┬
│    │    │    │    |
│    │    │    │    └ day of week (0 - 7) (0 or 7 is Sun)
│    │    │    └───── month (1 - 12)
│    │    └────────── day of month (1 - 31)
│    └─────────────── hour (0 - 23)
└──────────────────── minute (0 - 59)
```

Examples with the cron format:

42 \* \* \* \* : *Execute when the minute is 42 (e.g. 19:42, 20:42, etc.).*

0 0 \* \* 1 : *Execute at 00:00 on Monday*

#### Unsupported Cron Features

Currently, `W` (nearest weekday) and `L` (last day of month/week) are not supported. Most other features supported by popular cron implementations should work seamlessly, including `#` (nth weekday of the month).

[cron-parser](https://github.com/harrisiirak/cron-parser) is used to parse crontab instructions.

### "Every" notation

If you don't like writing cron expressions and prefer to configure your job to run every nth minute/hour/day. The starting time used as a reference is the first minute of the hour / first hour of the day / first day of the month, respectively.

(TODO)

Format: \[number]m|h|d

Examples:

"5m" = every 5th minute of the hour, starting from xx:00 (e.g. 04:00, 04:05, 04:10...)

"3h" = every 3rd hour, starting from 00:00. (e.g. 00:00, 03:00, 06:00...)

"7d" = At 00:00 on every 7th day-of-month, starting on the 1st (e.g. 2022-09-01 00:00:00, 2022-09-08 00:00:00, 2022-09-15 00:00:00, 2022-09-22 00:00:00, 2022-09-29 00:00:00, 2022-10-01 00:00:00)