JavaScript Lesson 5: Arrays — map, filter, reduce
Work with lists of data: create and index arrays, filter rows, map to new values, reduce to totals and groups, sort, and the spread…
Read article →JavaScript
JavaScript for data work and the web.
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JavaScript
JavaScript for data work and the web.
📄 10 articles⬇️ 10 with practice files🕒 Updated 12 Oct 2026
🎓 Start here: Rust Course → 🎓 Start here: Java Course → 🎓 Start here: R Course →JavaScript for Excel Users: Arrays, map, filter and reduce Explained
JavaScript for Excel Users: Arrays, map, filter and reduce Explained
Learn JavaScript’s most useful array tools — map, filter, reduce, sort — by comparing each one with an Excel formula you already know. Run…
Read article →Office Scripts: Automate Excel on the Web Without VBA
Office Scripts: Automate Excel on the Web Without VBA
Office Scripts bring automation to Excel for the web and Microsoft 365. Record a script, read the TypeScript it creates, and write a report-formatting…
Read article →JavaScript Lesson 8: Fetch — Getting Data From an API
JavaScript Lesson 8: Fetch — Getting Data From an API
Call web APIs with fetch, async/await, check response status, parse JSON, handle errors and offline cases, and where API keys must never go.
Read article →JavaScript Lesson 7: The DOM — Changing a Web Page
JavaScript Lesson 7: The DOM — Changing a Web Page
Make a page interactive: select elements with getElementById and querySelector, read input values, handle click events, change text and create elements.
Read article →JavaScript Lesson 6: Objects and JSON
JavaScript Lesson 6: Objects and JSON
Group related data in objects, access nested properties, destructure values, convert to and from JSON with JSON.stringify and JSON.parse — the format every API…
Read article →JavaScript Lesson 4: Functions and Arrow Functions
JavaScript Lesson 4: Functions and Arrow Functions
Write reusable functions with parameters, default values and return, the shorter arrow function syntax, and where functions are used as values.
Read article →JavaScript Lesson 3: Conditions and Loops
JavaScript Lesson 3: Conditions and Loops
Make decisions with if/else and the ternary operator, compare with ===, and repeat work with for, for...of over arrays and objects, and while.
Read article →JavaScript Lesson 2: Variables, Types and Strings
JavaScript Lesson 2: Variables, Types and Strings
Declare variables with const and let, understand numbers, strings and booleans, use template literals, format Indian numbers with toLocaleString, and common string methods.
Read article →JavaScript Lesson 1: Running JavaScript — Browser Console and Node
JavaScript Lesson 1: Running JavaScript — Browser Console and Node
Run your first JavaScript in the browser console and with Node.js, use VS Code, understand where JavaScript runs, and print output with console.log.
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