Full Stack Web Developer

Destructuring, the spread operator and the rest parameter are three features introduced with the modern version of JavaScript known as ES6 (ECMAScript 2015). They were designed to write shorter, clearer and more expressive code, especially when worki...

THEORETICAL RECAP An array of objects is simply an array whose elements are literal objects. It is the fundamental structure used to represent a collection of records: a list of products, users, orders, and so on. Each object holds properties (key/va...

THEORETICAL RECAP A literal object in JavaScript groups related data (properties) and behaviors (methods) inside a single structure delimited by curly braces. A property associates a key with a value (string, number, boolean, array, or even another o...

In JavaScript, an object is a data structure that groups together related values and behaviors under a single entity. Until now you have worked mainly with arrays, which store ordered lists of values accessed by numeric indexes. Objects are different...

THEORETICAL RECAP In JavaScript ES6+, arrays offer powerful methods to process collections of data without manually writing loops. The three core methods are: 'filter', which returns a NEW array containing only the elements that pass a test (a callba...

In your previous activities you learned how to loop over arrays with 'for', 'for... of' and 'while'. These classic loops work perfectly, but modern JavaScript offers dedicated array methods that make your code shorter, more readable and easier to rea...

In JavaScript, arrays are one of the most common data structures you will manipulate. An array is an ordered list of values, each stored at a numbered position called an index. The first element is always at index 0, the second at index 1, and so on....

THEORETICAL RECAP In JavaScript ES6+, an array is an ordered collection of values that you can traverse and transform. To compute statistics, you rely on a small set of core tools. A variable declared with 'const' or 'let' holds your data; a function...

THEORETICAL RECAP A task list manager in the console is a small program that stores items in memory and lets a user add, display, complete, and remove them. The core mental model is simple: your tasks live inside an array, and each task is an object ...

In JavaScript, an array (called a 'board' here, but the correct technical term is 'array') is one of the most important data structures you will use as a developer. An array is an ordered list of values grouped under a single variable name. Instead o...

Now that you have written your first functions, handled variables, applied conditions, and connected simple browser events, it is time to step back and adopt the mindset of a professional developer. Writing code that works is only half the job. Writi...

Writing a script that works is only half the job. Writing a script that another developer, or your future self, can read, understand, and modify quickly is what separates a beginner from a professional. This summary review consolidates everything you...

THEORETICAL RECAP An event is a signal the browser emits when something happens: a click, a key press, a page load. In JavaScript, you react to events by attaching an event handler (a function that runs when the event fires). The standard modern appr...

Until now, you have written JavaScript that runs from top to bottom, executing every instruction in order the moment the page loads. But real web applications are not static. They must react to what the user does: a click on a button, a key pressed o...

THEORETICAL RECAP Before starting the DOM, you will build a click counter using the browser's prompt() and alert() functions. A counter is simply a variable that stores a number and changes over time. The mental model is straightforward: you declare ...

Scope and hoisting are two fundamental concepts in JavaScript that explain where your variables and functions are accessible, and how JavaScript prepares them before running your code. Understanding these ideas will help you avoid many confusing bugs...

THEORETICAL RECAP A function is a reusable block of code that takes input (parameters), performs a task, and usually returns a value with the 'return' keyword. In ES6, you can declare functions in several ways: the classic declaration 'function add(a...

THEORETICAL RECAP A function in JavaScript is a reusable block of code that performs a task and, optionally, returns a value. In ES6, you can declare functions with the classic 'function' keyword or with arrow function syntax. A function usually take...

Functions are one of the most important building blocks in JavaScript. A function is a reusable block of code that performs a specific task. Until now, you have worked with variables, operators, and conditions. Functions allow you to group these inst...

THEORETICAL RECAP Determining whether a number is even or odd relies on the modulo operator (%), which returns the remainder of a division. A number is even when dividing it by 2 leaves no remainder, meaning n % 2 === 0. Otherwise, the remainder is 1...

THEORETICAL RECAP In JavaScript ES6+, a program often needs to react to information provided at runtime. You have already seen variables (let, const), primitive types (number, string, boolean), type conversions, arithmetic operators, template literal...

Until now, you have written programs that execute every line from top to bottom, without ever making a choice. But real applications constantly need to make decisions: show a welcome message only if a user is logged in, allow a purchase only if the a...

THEORETICAL RECAP Before starting, let's consolidate what you already know. In JavaScript ES6, you declare variables with `let` (reassignable) and `const` (fixed reference). Primitive types include numbers, strings, and booleans. A crucial point for ...

In the previous activities you learned how to declare variables using let and const, and you explored the primitive types of JavaScript such as numbers and strings. You also practiced simple type conversions. This chapter builds directly on that foun...

THEORETICAL RECAP In JavaScript, every value has a type: string, number, boolean, undefined, null, and others. Type conversion (or type casting) means transforming a value from one type into another. There are two kinds. Explicit conversion is when y...