The JavaScript Handbook (2025 edition)

One of my most popular handbooks is the JavaScript Handbook. Understandably, as JavaScript is such a popular programming language.

I first released this in 2020, 5 years ago.

Today I’m releasing an update.

Not much changed in the language, to be honest. JavaScript is super stable these days.

It’s mostly just cosmetic updates and minor / accuracy fixes, and clarifications, to make this book even better than it already was, and to make it up to date for the next 5 years!

Here’s a brief list of changes:

• Fixed some code examples
• Fixed some grammar and poor wording choices
• Modernized async content
• Type coercion clarification
• Improved how I explain arrays, and objects
• Clarified when you can omit braces in arrow functions (single statement)
• Consolidated default-parameter wording.
• Improved const/let consistency: const for non-reassigned bindings, let only when reassigned.
• Kept semicolon style consistent (no semicolons).

Download it now from https://flaviocopes.com/access/