Next level · 4/5 Career
React and Next.js: build modern web applications
The full job, with a portfolio
Two live React and Next.js applications in your portfolio
100,000 FCFA 24 h
View the next levelBy Mohamed Bah · Kolonell, a digital agency in Dakar
JavaScript: make a website come alive and interactive
An interactive catalog with a cart and WhatsApp ordering, coded in JavaScript by you
75,000 FCFA · 115 €
- 16 h of training
- Verifiable certificate
- Wave or Orange Money
- Online, at your own pace
I have a question (WhatsApp)
Quick enrolment in 30 s: invoice by email
I'd rather get a call back on WhatsApp
Programme
- 1The language fundamentals
- 2Functions, arrays and objects
- 3The DOM and events
- 4Forms, validation and local storage
- 5Asynchronous code, fetch and APIs
and 1 more module
Wave / Orange Money payment, access within 24 business hours
Possible earnings
With HTML, CSS and JavaScript, a beginner freelancer can charge 200,000 to 500,000 FCFA (about $330 to $830) for a business website with a calculator, an advanced form or an interactive catalog, and add one-off features at 50,000 to 150,000 FCFA (about $85 to $250) for small businesses in Dakar or Abidjan in 2026; your portfolio and your clients determine where you land in that range.
Indicative estimate, depending on your market, pace and work. No income is guaranteed.
Your instructor
Mohamed Bah
Founder of Kolonell, a digital agency and platform based in Dakar. He designs and deploys websites and web applications for SMEs in Senegal, Côte d'Ivoire and the diaspora, using the tools taught in this track.
See Kolonell’s work →Questions about this course
I have never written any JavaScript. Is this too advanced for me?
No. Module 1 starts the language from scratch. It only assumes you can write a page in HTML and CSS, which is what level 2 of the track covers.
Are the coding exercises graded?
Yes. Every coding exercise is checked automatically by tests in your browser: you immediately see what passes and what fails, with a message telling you what to fix.
Why not go straight to React?
Because React is JavaScript. Developers who skip this step get stuck on map, objects, asynchronous code and network errors. Sixteen hours here save you a lot of time at level 4.
Do we cover back-end development or databases?
No. Everything happens in the browser, with localStorage and public APIs. Servers, databases and authentication are covered at level 5, Full-stack developer.
Can the cart take a Wave payment?
Not at this level. The cart generates a prefilled WhatsApp order, which matches how many shops sell in Senegal. Real online payment requires a server, covered at level 5.
How much time should I plan?
About 16 hours including the exercises and the two projects. At 4 hours a week, allow 4 to 5 weeks.
How do I pay?
Via Wave or Orange Money. After enrolling you receive a pro forma invoice by email with the number to pay. Send the proof on WhatsApp: your access is activated within 24 business hours.
How long do I keep access?
For life, updates included. Learn at your own pace and revisit lessons as often as you need.
How do I get the certificate?
Complete the lessons, pass each module quiz with at least 70% and submit your final project: an instructor reviews and approves it (feedback within 5 working days). The certificate is then generated, with a unique number and a public verification page.
What you will be able to do
- Modern JavaScript ES2015+ (let, const, arrow functions, destructuring, template literals)
- Data processing with arrays and objects (map, filter, reduce, JSON)
- DOM manipulation and event handling
- Form validation and persistence with localStorage
- Asynchronous API calls with fetch and async/await
- Organizing code into ES modules and debugging with developer tools
What you will produce
- A library of tested utility functions: FCFA formatting, VAT calculation, phone number validation
- An interactive quote calculator connected to a form
- A sign-up form validated live with clear error messages
- A page that displays data loaded from a public API, with a loading state and error handling
- An online catalog with search, filters and a persistent cart
- A prefilled WhatsApp order generated from the cart
- A GitHub repository organized into ES modules with a README
Tools used
- VS Code
- Google Chrome and its developer tools
- JavaScript (ES2023)
- Node.js to run scripts
- JSON
- localStorage
- Fetch API
- GitHub
- Netlify
What you'll learn
- Write readable modern JavaScript: variables, types, conditions, loops and functions
- Work with arrays and objects using map, filter, reduce and find to process real data
- Select and modify the DOM and respond to user events
- Validate forms and calculate amounts in FCFA without rounding errors
- Store state in the browser with localStorage
- Load data from an API with fetch and async/await, handling errors and loading states
- Organize code into ES modules and debug it with the console and breakpoints
Prerequisites
- Level 2 of the track (HTML and CSS: build and lay out a real website) recommended, or the ability to build a responsive page in HTML and CSS
- A computer with VS Code and Google Chrome installed
- No prior JavaScript knowledge
- 4 hours a week for 4 to 5 weeks
About this course
Your website looks good, but it does nothing, and the JavaScript you once copied and pasted is still a black box. This course teaches the language from the ground up, for anyone who can already build a page in HTML and CSS. You learn to turn a brochure site into a tool a small business relies on: a live quote, a cart that remembers, a WhatsApp order ready to send.
First you build solid foundations: variables, conditions, loops, functions, arrays and objects. Then you take control of the page with the DOM and events, validate forms, calculate FCFA amounts with 18% VAT and store data with localStorage. The final modules cover fetch and async/await on 3G connections, then ES modules, debugging and deployment.
Plan on 16 hours: 6 modules, 30 lessons and 83 graded exercises, more than half of them coding exercises, with a quiz in every module. Two projects assessed against clear criteria punctuate the course: a quote calculator for a Dakar service provider, then an interactive catalog with a cart and WhatsApp ordering. A certificate you can verify online wraps it up.
You leave with a library of tested utility functions, a page powered by a public API, and an online catalog with search, filters and a persistent cart. With HTML, CSS and JavaScript, a beginner freelancer can charge 200,000 to 500,000 FCFA (about $330 to $830) for a website with a calculator or an interactive catalog, and 50,000 to 150,000 FCFA (about $85 to $250) for one-off features for small businesses in Dakar or Abidjan in 2026. Your portfolio decides where you land in that range, and no income is guaranteed.
This is level 3 of the Web Development track: it builds on HTML and CSS (level 2) and lays the groundwork for React and Next.js (level 4).
Who it is for: HTML and CSS developers, computer science students, self-taught learners and freelancers in Dakar, Abidjan, Bamako, Cotonou or the diaspora who can build a page and want to make it interactive: calculations, forms, a cart, data loaded from an API.
Curriculum
A module-by-module path: lessons, exercises, quizzes and projects to submit.
Module 1· 13 exercises
The language fundamentals
You write your first JavaScript programs with variables, types, conditions and loops, and you read error messages without panicking.
- Where JavaScript runs: the browser, the console and a file linked to the pageFree preview3 exercises15 min
- Variables and types: let, const, numbers, strings and booleansFree preview3 exercises18 min
- Conditions and operators: deciding based on an amount or a delivery zoneFree preview3 exercises18 min
- Loops: repeating a calculation over a list of ordersFree preview4 exercises15 min
- Module handout (PDF)Free preview5 min
- Quiz: the language fundamentalsModule quiz
Module 2· 14 exercises
Functions, arrays and objects
You split your code into reusable functions and process lists of products or customers with array methods.
- Functions: parameters, return values and arrow functions3 exercises18 min
- Arrays and methods: map, filter, find and reduce3 exercises20 min
- Objects, destructuring and JSON3 exercises18 min
- Numbers, dates and FCFA amounts: formatting without errors5 exercises15 min
- Module handout (PDF)5 min
- Quiz: functions, arrays and objectsModule quiz
Module 3· 13 exercises
The DOM and events
You modify the page from JavaScript and respond to clicks, typing and scrolling.
- The DOM: selecting elements and changing their content3 exercises18 min
- Creating elements and rendering a list from an array2 exercises18 min
- Events: click, input, submit and delegation4 exercises18 min
- Dynamic CSS classes: tabs, mobile menu and accordion4 exercises15 min
- Module handout (PDF)5 min
- Quiz: the DOM and eventsModule quiz
Module 4· 14 exercises
Forms, validation and local storage
You build forms that guide the user and you store data in the browser.
- Reading a form with FormData and preventing the default submission3 exercises15 min
- Live validation: Senegalese and Ivorian numbers, emails and required fields3 exercises18 min
- Dynamic calculations: quotes, discounts, 18% VAT and delivery fees4 exercises18 min
- localStorage: keeping a cart or a draft after the page is closed4 exercises15 min
- Module handout (PDF)5 min
- Quiz: forms, validation and storageModule quiz
- Quote calculator for a Dakar service providerProject to submit
Module 5· 15 exercises
Asynchronous code, fetch and APIs
You load data from a JSON file or a public API, handling waiting times, errors and slow connections.
- Understanding asynchronous code: the event loop, callbacks and Promises3 exercises18 min
- async and await: writing readable asynchronous code3 exercises15 min
- fetch: loading a JSON file and a public API4 exercises18 min
- Loading states, network errors and 3G connections5 exercises15 min
- Module handout (PDF)5 min
- Quiz: asynchronous code, fetch and APIsModule quiz
Module 6· 14 exercises
Organize, debug and publish
You structure a real project into modules, fix bugs methodically and publish a clean application.
- ES modules: import, export and splitting up a project4 exercises15 min
- Debugging methodically: the console, breakpoints and the Network tab4 exercises18 min
- Handling errors: try, catch and useful messages for the user3 exercises15 min
- Best practices, README and deploying a JavaScript application3 exercises15 min
- Module handout (PDF)5 min
- Quiz: organize, debug and publishModule quiz
- Final project: interactive catalog with a cart and WhatsApp orderingCapstone
Certificate included
Your certificate at the end
A numbered certificate with your validated skills, a public page and a verification QR code. Add it to LinkedIn in one click.
Kolonell Academy
Verified by Kolonell AcademyCertificate of skills
Your name
has completed and validated the course
JavaScript: make a website come alive and interactive
Skills developed
- Modern JavaScript ES2015+ (let, const, arrow functions, destructuring, template literals)
- Data processing with arrays and objects (map, filter, reduce, JSON)
- DOM manipulation and event handling
- Form validation and persistence with localStorage
- Asynchronous API calls with fetch and async/await
- Organizing code into ES modules and debugging with developer tools
Number KOL-CERT-2026-XXXXX
Mohamed Bah
Founder, Kolonell Academy
After the course
What you get once the course is complete
A verifiable certificate
Each certificate has a number anyone can verify online, and you can add it to your LinkedIn profile in one click.
Your CV reviewed and improved
Upload your CV from your profile: our team reviews it and helps you make it clearer and more convincing.
Access to the talent pool
Learners who complete the course can join the Kolonell talent pool. Entry is earned: course completed, exercises submitted. Kolonell also draws on it for its own hiring.
Optional services, free for learners. This is not a promise of employment.
Course poster
Download the poster to print it, send it to your employer or share it with colleagues. The full programme details every module.
Our commitments
- Lifetime access, updates included
- Publicly verifiable certificate
- Wave / Orange Money payment, activation within 24 business hours
- Ask an instructor from any lesson, answer within 2 working days