Today I Learned

A Hashrocket project

7 posts by mattpolito @mattpolito

Truncate an Array

Every time I go to truncate and array in JavaScript, I have to look up the syntax. It’s something that makes me angry.

Did you know that there is an oddly easier way to do it without reaching for splice() or slice()?

const collection = [4,6,9,1,12,42];
collection.length = 3;

collection is now [4,6,9]

Hopefully I can remember this one!

Install `capybara-webkit`

Turns out capybara-webkit’s has a dependency on qtwebkit which has been removed from the qt library package. You’ll have the pleasure of finding this out when you run into this grand error:

Project ERROR: Unknown module(s) in QT: webkitwidgets

To get around this, you can install a previous version of qt using brew via:

brew install qt@5.5

Now reload your terminal and ensure that you can run qmake. Once that is all good, go ahead and reinstall/bundle capybara-webkit.

Don’t let this stump you for longer than it did me!

Using pessimistic gem version to catch betas

The trouble with pessimistic (~>) versioning is that it still won’t catch pre-release library versions… or will it.

It actually can allow ‘beta’ versions by adding an ‘x’ to the version you’d like to catch.

gem "rails", "~> 5.x"

Since ‘beta’ versions (5.0.0.beta3) actually register as higher than 5.0.0, the pessimistic operator will not catch the beta version. Gem versioning shows any version with a letter as ‘pre-release’ which is how beta3, rc1, alpha versions work.

Using the ‘x’ as a wildcard will allow pre-release gem versions to be caught.