Support Steps with Ranges

[sarahsporck]

Hi there!

First of all - awesome library - easy to use, easy to extend.

So I'm myself working with the crontab format and I found it would be awesome if this library would support more complex steps for hours, minutes and basically every field.

What is already working are these step definitions: '*/10' aka 'every 10 minutes'
What is defined in the crontab manual, but does not work are steps with ranges:

• '5-20/5' - every 5th minute from 5 through 20
• '5/5' - every 5th minute from 5 through 59

The ReactJS Cron library already supports that as far as I see. And whithout considering the UI for it, it probably already is quite simple.

As a note:
Initially I thought about implementing it myself for my use case in my project, but found that the Segment Factories are not exported in the index.ts, and without them it is quite tedious to extend e.g. the minute field. So that would also be awesome!

Thanks in advance :) And once again awesome library.

[abichinger]

Hi,

Thanks! I'm glad you like it.

Steps with ranges are partially supported. The libaray can parse cron expressions that include steps with ranges but converts them into a separated list of values. This means you can input steps with ranges, but the package can't output them in that format.

• 5-20/5 * * * * becomes 5,10,15,20 * * * *

The package already includes code to convert 5,10,15,20 back to 5-20/5 (see EverySegment.fromArray). What still needs to be done is to ensure that the localization also supports ranges with steps.

'5/5' - every 5th minute from 5 through 59

Maybe I missed it, but I don't see a definition for fields like 5/5 on https://linux.die.net/man/5/crontab

Step values can be used in conjunction with ranges. Following a range with "<number>" specifies skips of the number's value through the range. For example, "0-23/2" can be used in the hours field to specify command execution every other hour (the alternative in the V7 standard is "0,2,4,6,8,10,12,14,16,18,20,22"). Steps are also permitted after an asterisk, so if you want to say "every two hours", just use "*/2".

Contributions are always welcome. Would you like to create a PR for this?