Datetoken

Installing

npm i datetoken

Examples

Most probably you will be dealing with simple presets such as yesterday or the last 24 hours.

>>> const datetoken = require('datetoken');
>>> console.log(new Date())
2018-10-18 14:08:47
>>> datetoken('now-d/d')  # Start of yesterday
2018-10-17 00:00:00
>>> datetoken('now-d@d')  # End of yesterday
2018-10-17 23:59:59

Motivation

This package aims to solve a set of needs present in applications where dates need to be represented in a relative fashion, like background periodic tasks, datetime range pickers... in a compact and stringified format. This enables the programmer to persist these tokens during the lifetime of a process or even longer, since calculations are performed in the moment of evaluation. Theses tokens are also useful when caching URLs as replacement of timestamps, which would break caching given their mutability nature.

Some common examples of relative tokens:

| | From | To | | ------------------------------ | -------------- | ------------- | | Today | now/d | now | | Yesterday | now-d/d | now-d@d | | Last 24 hours | now-24h | now | | Last business week | now-w/bw | now-w@bw | | This business week | now/bw | now@bw | | Last month | now-1M/M | now-1M@M | | Next week | now+w/w | now+w@w | | Custom range | now+w-2d/h | now+2M-10h | | Last month first business week | now-M/M+w/bw | now-M/+w@bw | | This year | now/Y | now@Y | | This quarter | now/Q | now@Q | | First quarter (Q1) | now/Q1 | now@Q1 | | Second quarter (Q2) | now/Q2 | now@Q2 | | Third quarter (Q3) | now/Q3 | now@Q3 | | Fourth quarter (Q4) | now/Q4 | now@Q4 |

As you may have noticed, token follow a pattern:

• The word now. It means the point in the future timeline when tokens are parsed to their datetime form.

• Optionally, modifiers to add and/or subtract the future value of now can be used. Unsurprisingly, additions are set via +, while - mean subtractions. These modifiers can be chained as many times as needed. E.g: now-1M+3d+2h. Along with the arithmetical sign and the amount, the unit of time the amount refers to must be specified. Currently, the supported units are:

  • s seconds
  • m minutes
  • h hours
  • d days
  • w weeks
  • M months
  • Y years
  • Q quarters

• Optionally, there exist two extra modifiers to snap dates to the start or the end of any given snapshot unit. Those are:

  • / Snap the date to the start of the snapshot unit.
  • @ Snap the date to the end of the snapshot unit.

  Snapshot units are the same as arithmetical modifiers, plus bw, meaning business week. With this, we achieve a simple way to define canonical relative date ranges, such as Today or Last month. As an example of the later:

  • String representation: now-1M/M, now-1M@M
  • Being today 15 Jan 2018, the result range should be: 2018-01-01 00:00:00 / 2018-01-31 23:59:59

Compatibilty

• For node>=8.10 use datetoken==1.x.x
• Otherwise use datetoken==0.x.x

Issues

• Business week snapshots might not be reliable in timezones where weeks start in days other than Monday