As this is posted, I am starting a talk at WordCamp Atlanta, 2019. I am speaking on internationalization (i18n) in WordPress. Below is a link to the slide from my talk as well as additional resources and references that I have found helpful in my own learning and development endeavours.
The slides include code examples with short descriptions. All text should be able to be copy-pasted from the PDF.
The following is a link to a quick plugin I wrote showing different usages of WP translation functions. It also includes a working example of translations in JS files.
Example i18n plugin for WordPress (GitHub)
Resources & References
* Page may contain some outdated information