But do I have to?

Yes! WordPress is increasingly using more and more JS, whether in the admin, themes, or plugins.

The founder of WordPress pointed out this evolution and encouraged us to “Learn JavaScript Deeply”.

And the current priorities for WordPress development — customization, the editing experience, and the REST API — all require JS.

So, if you want to develop for WordPress, learning JS in addition to PHP is a necessity.

Article: JavaScript and WordPress

The Landscape

The JavaScript world is big, and seems to only be getting bigger and more complicated everyday. You can get caught up in frameworks and tooling, but here are some helpful places to get a grasp on the JavaScript world and how everything fits.

• Article: State of the JavaScript Landscape: A Map for Newcomers
• Article: A Survey of the JavaScript Landscape for WordPress Developers

The Language

• Article: JS for WordPress people
• Book: You Don’t Know JavaScript
• Course: JavaScript30: Become comfortable with both JavaScript fundamentals and working in the DOM without libraries, frameworks, or any other distractions
• Course: JS for WordPress Master Course

ES6

• Article: Anatomy of a Modern JS Application
• Article: Preparing for ES6
• Article: Get Started with ES6
• Articles: ES6
• Course: ES6 for Everyone
• Tool: Babel
• Article: ES8
• Article: The Proposed Features Process