programming

ditch moment.js for date-fns

I was a moment.js fan until I heard about date-fns. One of the biggest problem with moment.js is that date operations such as .subtract or .add mutates the object! Take the following code for example:

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var now = new moment()
var prev = now.subtract(5, 'days')
// both prev and now are 5 days ago
// if you need to preserve 'now', you need to do something like
var prev = now.clone()
prev.subtract(5, 'days')
// prev will be 5 days ago but now remains the initial value

I was surprised in a great deal to find out such weird behavior through googling and bugs in my projects. To make things worse, moment’s doc dosn’t tell you clearly that calling .subtract() or .add() would mutate the original object.

Another issue working with moment.js is that Moment object is not a native javascript Date object, which means conversions are required, which in turn creates two new problems:

  1. Bad performance
  2. Not straigh-forward to work with because you will need to call .toDate() to convert Moment into Date, or moment() to convert Date (or date string) into Moment

date-fns is billed as the underscore for Dates. If you are a big fan of underscore (or lodash), you know what that means.

Tldr; here’s the date-fns version of the previous code snippet:

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var subDays = require('date-fns/sub_days');	// note you can import only the function you need
var now = new Date();
var prev = subDays(now, 5);
// now remains the initial value

I have converted some of my existing projects into using date-fns and the experience has been awesome since I don’t have to live with the annoyance that moment.js brings.

Don’t just take my words, go give https://date-fns.org/ a try, or simply

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npm i date-fns

if you are already convinced.

Update: It turns out I am not the only one who feels the need for the switch. Dan Abramov, the creator of redux, mentioned this in late 2016
https://twitter.com/dan_abramov/status/805030922785525760?lang=en