JavaScript runs every web page, Office Scripts in Excel, Google Apps Script and Node.js tools. Eight lessons from the console to arrays, objects, the DOM and fetching data from APIs, with tested scripts.

1. 1JavaScript Lesson 1: Running JavaScript — Browser Console and NodeRun your first JavaScript in the browser console and with Node.js, use VS Code, understand where JavaScript runs, and print output with…
2. 2JavaScript Lesson 2: Variables, Types and StringsDeclare variables with const and let, understand numbers, strings and booleans, use template literals, format Indian numbers with toLocaleString, and common string…
3. 3JavaScript Lesson 3: Conditions and LoopsMake decisions with if/else and the ternary operator, compare with ===, and repeat work with for, for...of over arrays and objects, and…
4. 4JavaScript Lesson 4: Functions and Arrow FunctionsWrite reusable functions with parameters, default values and return, the shorter arrow function syntax, and where functions are used as values.
5. 5JavaScript Lesson 5: Arrays — map, filter, reduceWork with lists of data: create and index arrays, filter rows, map to new values, reduce to totals and groups, sort, and…
6. 6JavaScript Lesson 6: Objects and JSONGroup related data in objects, access nested properties, destructure values, convert to and from JSON with JSON.stringify and JSON.parse — the format…
7. 7JavaScript Lesson 7: The DOM — Changing a Web PageMake a page interactive: select elements with getElementById and querySelector, read input values, handle click events, change text and create elements.
8. 8JavaScript Lesson 8: Fetch — Getting Data From an APICall web APIs with fetch, async/await, check response status, parse JSON, handle errors and offline cases, and where API keys must never…

Related: JavaScript arrays for Excel users, Office Scripts course.