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Modern JavaScript

The modern JavaScript you actually use in React and production code — spread & rest, default parameters, object shorthand, the array-method toolkit (map/filter/reduce), safe data access, and async patterns. The bridge from vanilla JS to frameworks.

Prerequisites:📊Data Explorer ⚙️Function Factory

What Modern JavaScript Means

Meet the modern JavaScript toolkit — the features added since 2015 that make code shorter, safer, and that every framework like React is built on.

Default Parameters

Give function parameters fallback values so callers can leave them out — the clean modern replacement for the old `x = x || fallback` trick.

Spread and Rest (...)

Use the ... operator to copy and combine arrays and objects without mutating them — the exact technique React state updates rely on — and to collect extra arguments.

Object Shorthand & Computed Keys

Write objects with less repetition using property shorthand, and build objects with dynamic keys using computed property names — both everywhere in React.

Transforming Data with map

Use .map() to turn one array into another by transforming every item — the single most important array method in React, where it powers every rendered list.

Selecting Data: filter, find, some, every

Keep only the items you want with filter, grab the first match with find, and ask yes/no questions about a list with some and every.

Boiling Down Data with reduce

Use .reduce() to collapse an array into a single value — a total, a maximum, a count, or a grouped object. The most powerful (and most feared) array method, made simple.

Chaining: Data Pipelines

Chain map, filter, and reduce together to turn raw data into exactly what your UI needs — the data-shaping every React component does before it renders.

Destructuring in Practice

Pull values straight out of objects and arrays — in function parameters (the React props pattern), in the useState shape, and while looping objects with Object.entries.

Safe Data Access: ?. and ??

Read deeply nested or possibly-missing data without crashing using optional chaining (?.), and supply clean fallbacks with nullish coalescing (??).

Async Patterns & Promise.all

Recap async/await, then run several async tasks at once with Promise.all — the difference between a snappy page and a slow one.

Capstone: A Sales Summary

Combine filter, map, reduce, and object shorthand to turn a raw array of orders into a clean summary — exactly the data-shaping a real dashboard does.

Codelab: A Shopping-Cart Module

Build a real shopping-cart data layer in a plain HTML file — immutable add/remove with spread and filter, totals with reduce — and run it in your browser.