JavaScript
In depthProgramming language
Also known as: JS, ECMAScript, ES
The language of the web. Runs in every browser, and on the server with Node.js. Dynamically typed.
JavaScript, explained
Written by EduVerseWhat it is
JavaScript is the programming language built into every web browser, and despite the name it has little to do with Java. It makes pages interactive: reacting to clicks, checking forms, loading data without a reload. Through Node.js it also runs on servers and in command-line tools.
Why teams use it
Browsers run JavaScript directly, so anyone who builds frontends needs it, even when they write TypeScript that compiles to it. Using one language for both browser and server also appeals to small teams. The flip side of its dynamic typing is that mistakes like a misspelled property only show up when the code runs.
An example from work
A button on your team’s site does nothing when you click it. The browser console shows “Uncaught TypeError: Cannot read properties of undefined”, often because the code used data that hadn’t arrived from the API yet. It’s an error every JavaScript developer learns to recognize quickly.
Our own explanation, not a quote from the book.
In the book
Sentences from The Software Realm, Decoded that mention JavaScript, exactly as printed.
Senior developer “High-level languages like Python, JavaScript, and Java have ’automatic transmissions’, they manage memory for you.”
Chapter 2 · 2.2 The Languages Ecosystem: Choosing Your Tools · pp. 48–49Open in the free preview
Peter “So JavaScript manipulates the DOM, not the file?”
Chapter 4 · 4.4.1 The DOM: Your Live Document · pp. 95–96Open in the free preview
9 more passages about JavaScript in the full book
Read every conversation where JavaScript comes up, with the interactive slides and demos.
Where it fits
Frontend interactivity, server-side with Node.js, full-stack development
Coverage in the book
Covered in depth: multiple pages with explanations, examples and simulations.
