JavaScript Certification
One paper across the whole language: how the web works, everyday JavaScript, then scope, prototypes and promises, and finally the event loop, performance, workers and browser security. Sat in one two-and-a-half-hour sitting.
- Sitting
- 2½ hours
- Questions
- 65
- Pass mark
- 70%
- Price
- ₹199$9.99
Sit this when you can do these without looking them up
This is not a certificate of attendance. It is 65 questions in 2½ hours at 70% with no partial credit and one attempt, and roughly a third of the paper is foundations — the certificate is for the whole language, not the parts you enjoyed.
- Explain why
0.1 + 0.2 !== 0.3, and what==does that===does not - Predict the order of a snippet mixing
setTimeout, a resolved promise and plainconsole.log - Say what
thisis in four different call patterns, and repair a callback that lost it - Follow a property lookup up the prototype chain, and say what
classgives you that a constructor function does not - Describe a bug a shallow copy caused you, and what you would reach for instead
- Name the defence against XSS that still holds when an attacker controls the whole string
- Say what layout thrashing is, and how you would find it in a profile
If several of those are unfamiliar, the course below is free and covers all of it. If you would rather find out than guess, there is a practice paper at the same level — ten questions, marked as you go, no account, nothing recorded.
Take the free practice paperSyllabus
Every paper is drawn to this mix, so the weights are a promise rather than a guide. The numbers are how many of the 65 questions come from each area.
- 2
How the web works
Clients and servers, DNS, requests and responses, status codes, and where your code runs.
- 4
Values and types
let and const, the primitive types, null versus undefined, and type coercion.
- 3
Text and numbers
String methods, template literals, arithmetic, rounding, and converting between the two.
- 3
Control flow
Comparison, truthiness, if and else, ternaries, switch, loops, and error handling with try, catch, finally, and throw.
- 4
Functions
Declarations, arrow functions, parameters and defaults, return values, scope, and debugging with call stacks.
- 4
Arrays and objects
Creating and reading both, nesting, destructuring, spread, map/filter/reduce, Map, Set, and persisting data with localStorage.
- 2
The browser
The DOM as a tree, selecting and changing elements, events, forms, and fetching API data with fetch().
- 4
Scope and closures
The scope chain, block versus function scope, closures, and the temporal dead zone.
- 3
this and binding
Call patterns, call, apply and bind, arrow functions, and losing this in a callback.
- 4
Objects and prototypes
The prototype chain, classes, inheritance, private fields, and getters and setters.
- 3
Destructuring and spread
Nested destructuring, defaults, rest, shallow copying vs structuredClone, optional chaining (?.) and nullish coalescing (??).
- 3
Modules
Named and default exports, module scope, dynamic import, and ESM versus CommonJS.
- 5
Promises and async
States, chaining, error propagation, async and await, the combinators, and cancellation.
- 4
The event loop
Macrotasks and microtasks, ordering, starvation, animation frames, and Node's phases.
- 3
Iterators and generators
The iteration protocol, writing iterators, generators, laziness, and async iteration.
- 3
Functional patterns
Purity, composition, currying, memoisation and its cache costs, and recursion.
- 4
Performance
The pixel pipeline, layout thrashing, the frame budget, Core Web Vitals, and measuring.
- 3
Workers
Dedicated workers, structured clone, transferables, and what a worker cannot reach.
- 4
Security
Same-origin, CORS, XSS and its defences, CSP, CSRF, and where tokens belong.
Everything on this syllabus is taught free
The JavaScript Masterclass course covers the whole syllabus above across 33 lessons, with a playground in each one. Work through it first — the exam is the same material under a clock.
Open the JavaScript Masterclass courseWhat sitting it is like
The exam opens full screen with a countdown, a question at a time, and a grid showing what you have answered and what you have flagged to come back to. Nothing is submitted until you say so, or the clock reaches zero.
Every answer saves to the server as you give it. If your laptop dies at question forty, sign back in and you will find question forty exactly as you left it — with however much time was left still ticking, because the clock does not pause.
Leaving full screen or switching tabs is noted but does not end your exam. It is a record, not a trap: nobody is auto-failed for a notification stealing focus.
When it ends you get your mark, a topic-by-topic breakdown, and every question with the right answer and an explanation — whether you passed or not. Passing also produces a certificate with a link anyone can verify.