Saturday, February 24, 2018

A shopping hours calculator

Say you have a small mom&pop online shop that sell widgets.

If you have (a) dedicated personnel that calls customers on the phone to confirm an order w/ its shipping details, & (b) such a 'department' usually work regular hours & isn't available 24/7.

(This is the exact scheme to which the vast majority of Ukrainian online shops still adhere to.)

This is how a shop gets its 1st bad review: it's Friday evening 7 o'clock, a client places an order for a widget & waits for a call that doesn't come until the Monday morning. The enraged client then may even try to call the shop during the weekend not realising it's closed.

One of the possible solutions to this is to have a note (on a page where customers review their orders) that at this very moment the person that can confirm/discuss their order is offline.

How do you calculate that? It's an easy task if you work the same hours every day of the year but for a small online shops it's often not the case. Not only there are a handful of the official gov holidays, some holidays have moveable dates (Easter), sometimes a holiday falls on a weekend & must be transferred to the next working day. What if your customer department has a lunch break like everyone else? A client should be able to see that the call they're so eagerly waiting for is going to come in an hour, not in 2 minutes.

So I wrote a small JS library to help w/ that: You can use it on either server or client side. The basic idea is: we fetch a .txt file (a calendar) & check for a status "is the shop open" that simultaneously tells us when the shop will be open/closed. We fetch the cal only once & do the checking however often we care.

The calendar DSL looks like this:

-/-                 9:00-13:00,14:00-18:00
1/1                 0:0-0:0                   o   new year
easter_orthodox     0:0-0:0                   o
fri.4/11            6:30-23:00                -   black friday
sat/-               10:30-17:00
sun/-               0:0-0:0

On a client side, you can test it w/ adding to .html: <script src="shopping_hours.min.js"></script> & to .js:

async function getcal(url) {
    let cal = await fetch(url).then( r => r.text())
    return shopping_hours(cal)  // parse the calendar

getcal('calendar1.txt').then(sh => {

which outputs smthg like {status: "open", next: Sat Feb 24 2018 17:00:00 GMT+0200 (EET)}. See the github page for the details.