JavaScript in Practice: ES6+, Array Methods, Async & Fetch
Trace modern JavaScript the way it really runs: let/const, arrow functions, destructuring, spread, map/filter/reduce, modules, classes, promises, async/await, JSON and fetch with error handling, with every answer checked as you go.
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About this course
In this intermediate course you trace modern JavaScript the way it really runs. Each of the 20 lessons is a lab: you read real code next to fictional shop data and predict exactly what it returns – running totals with let and const, default parameters, destructuring, spread and rest, map, filter, reduce and sort chains, ES module imports and tree-shaking, classes with getters, optional chaining and ??, timer order, promise chains, sequential versus parallel await, JSON payloads and fetch with status checks and retries. Every answer is checked instantly, and a final project and exam lead to your certificate. The first lesson is free.
Lessons
- let, const & Block Scope: Tracing a Cart TotalFree
- Template Literals & String Padding: Printing Receipt Lines Locked
- Arrow Functions & Default Parameters: A Shipping Calculator Locked
- Destructuring: Unpacking Orders with Defaults Locked
- Spread & Rest: Merging Settings and Variadic Functions Locked
- Object.keys, values & entries: A Stock Report from One Object Locked
- map(): Gross Prices and Tags for Every Item Locked
- filter(): Keeping the Orders That Match Locked
- reduce(): Folding a Cart into One Value Locked
- find, findIndex, some & every: Asking Questions of an Array Locked
- sort() and Method Chaining: A Top-3 Widget Locked
- ES Modules: import, export & What Ends Up in the Bundle Locked
- Classes, Getters & Private Fields: A Cart Object Locked
- Optional Chaining & Nullish Coalescing: Safe Defaults Locked
- Callbacks & setTimeout: Predicting the Order of Logs Locked
- Promises: Chaining then, catch & finally Locked
- async/await: Sequential vs Parallel Loading Locked
- JSON.parse & JSON.stringify: What Goes over the Wire Locked
- fetch & Error Handling: Status Codes and Polite Retries Locked
- Final Project: The Order Dashboard Pipeline Locked