Junior Web Developer study guide
Junior Web Developer · Work through your exam, one topic at a time.
The Junior Web Developer certification is an entry-level credential for people who build and maintain websites and want to demonstrate job-ready fundamentals to employers. It suits career changers, bootcamp graduates, and self-taught developers preparing for a first developer role. The Junior Web Developer study guide has 9 sections and about 2,992 words.
01HTML and Semantic Markup
The HTML and Semantic Markup domain tests whether you can build a valid document and pick elements for meaning rather than appearance. Questions target document metadata, content models, void elements, heading hierarchy and the sectioning and landmark elements.
358 words, about 2 min02CSS Layout and Responsive Design
The CSS Layout and Responsive Design domain tests the box model, the cascade, Flexbox and Grid, positioning, and how layouts adapt across viewport sizes. box-sizing: border-box makes width include padding and border; most resets apply it globally.
316 words, about 2 min03JavaScript Fundamentals
The JavaScript Fundamentals domain tests the language core: types and coercion, scope, functions and closures, this , arrays and objects, prototypes, modules, and the asynchronous model. There are seven primitives - string, number, bigint, boolean, undefined, symbol, null - plus objects.
338 words, about 2 min04DOM Manipulation and Events
The DOM Manipulation and Events domain tests how you select and modify nodes, how events propagate, and how to write handlers that stay correct as content changes. querySelector and querySelectorAll take CSS selectors and return a static NodeList .
320 words, about 2 min05Web Accessibility and Semantic HTML
The Web Accessibility and Semantic HTML domain tests WCAG-driven practice: whether every user can perceive, operate and understand the interface, including people using keyboards and assistive technology. WCAG is organised by POUR - perceivable, operable, understandable, robust - with levels A, AA and AAA; most legal requirements reference AA.
310 words, about 2 min06HTTP, Forms, and Client-Server Communication
The HTTP, Forms, and Client-Server Communication domain tests how browsers and servers exchange data: request methods, status codes, headers, caching, cross-origin rules and form submission. GET is safe and idempotent and should never change state; PUT and DELETE are idempotent; POST is neither.
313 words, about 2 min07Version Control and Development Tooling
The Version Control and Development Tooling domain tests everyday Git fluency - the three trees, branching, history rewriting - plus the package and build tooling around a modern front-end project. Git tracks the working tree, the index (staging area) and the repository of commits.
350 words, about 2 min08Web Security Fundamentals
The Web Security Fundamentals domain tests the browser's security model and the defensive coding that follows from it: same-origin policy, injection, session attacks and transport protections. Two URLs share an origin only if scheme, host and port all match.
336 words, about 2 min09Testing and Debugging
The Testing and Debugging domain tests whether you can prove code works and diagnose it when it does not: test layers, isolation, assertions, and the DevTools and workflow habits that shorten feedback loops. Unit tests are fast and numerous, integration tests check modules together, and end-to-end tests drive a real browser, making them slow and brittle - keep few of them.
351 words, about 2 min