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JavaScript Basics

10 lessons

Learn JavaScript from the beginning — variables, functions, arrays, objects, DOM, and async.

  1. 1

    JavaScript Overview

    What JavaScript is, where it runs, and why it is essential for modern web development.

  2. 2

    JavaScript Variables

    How to declare variables with let, const, and var, and the rules that govern them.

  3. 3

    JavaScript Data Types

    The primitive and reference types in JavaScript, and how typeof helps you inspect them.

  4. 4

    JavaScript Functions

    Function declarations, arrow functions, parameters, return values, and closures.

  5. 5

    JavaScript Arrays

    Creating, indexing, and iterating arrays, plus the essential map, filter, and reduce methods.

  6. 6

    JavaScript Objects

    Objects as key-value collections, property access, destructuring, and the spread operator.

  7. 7

    Conditions

    if/else, switch, ternary operator, truthy/falsy values, and short-circuit evaluation.

  8. 8

    Loops

    for, while, for...of, for...in, and how to break and continue iteration.

  9. 9

    DOM

    Selecting elements, handling events, and updating the page with the Document Object Model.

  10. 10

    Async JavaScript

    Callbacks, promises, async/await, and fetching data from APIs without blocking.

Build real projects

Apply what you learned by building guided projects with starter code and solutions.

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Decode error messages

Plain-English explanations of common errors — what they mean, why they happen, and how to fix them.

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