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← Introduction to JavaScript
○What is JavaScript?○Your First JavaScript Code○Data Types○Type Checking○Inspect Values in the Console○Inspect the Queue Report○Trace a Faulty Calculation○Repair the Score Calculation✦Module Quiz
○Declaring Variables○let and const in Practice○Operators○Type Conversion○Group and Convert Expense Inputs○Calculate the Event Expense Total○Track a Changing Points Tally○Adjust a Ticket Price✦Module Quiz
○Conditionals○Demo: Combined Conditions Before FizzBuzz○Challenge: FizzBuzz Announcer○Switch Statement○Demo: Switch a Venue Sign○Challenge: Power Loadout○For Loops○While Loop○Break and Continue○Demo: Stop a Ticket Scan○Challenge: Number Guess Referee○Demo: Rainfall Routing Walkthrough○Exercise: Score Batch Report✦Module Quiz
○Defining Functions○Arrow Functions○Scope○Closures○Project - Calculator○Function Expressions○Demo: Ticket Pricing Walkthrough○Exercise: Shipping Labels with Defaults○Demo: Seat Ledger Closure Walkthrough○Exercise: Private Budget Ledger✦Module Quiz
○Arrays○Demo: Student Scoreboard○Challenge: Student Course Scoreboard○Array Mutation Methods○Array Slice and Concat○Array Iteration Methods○Multidimensional Arrays○Destructuring○Array Reverse and Sort○Array Fill○Array Find and Includes○Array Flat and FlatMap○Array Reduce, Some, and Every●Demo: Charging Rack Restock Report○Exercise: Pantry Restock Plan✦Module Quiz
○Object Key-Value Pairs○Student Course Record○Object Methods and Destructuring○Map and Set Collections○Playlist Lookup○Number and BigInt Boundaries○Ticket Ledger○JSON○Math and Date○Date Basics○Demo: Supply Bin Audit○Exercise: Volunteer Shift Audit○Demo: Workshop Attendance Feed○Exercise: Parcel Scan Feed✦Module Quiz
○String Methods○Template Literals○Regular Expressions○Demo: Build a Reminder with Template Literals○Exercise: Format Pantry Pickup Messages○Demo: Validate a Time Slot with Regex○Exercise: Validate Storage Shelf Labels✦Module Quiz
○Higher-Order Functions○Callbacks○map, filter, and reduce○Demo: Student Register with map○Challenge: Student Register○Recursion○Project - Data Transform Pipeline○Demo: Handle an Error-First Callback○Exercise: Report Seat Reservation Results○Demo: Summarize Completed Bike Rides○Exercise: Summarize Delivered Parcels✦Module Quiz
○Demo: A notebook object○OOP Introduction○Demo: Independent workshop passes○Classes○Demo: An inherited notice○Inheritance○Demo: A private seat counter○Encapsulation○Demo: Equipment desk checkout○Project: Library Checkout✦Module Quiz
○Demo: Callback Timing○Exercise: Asynchronous JavaScript○Demo: Promise Rehearsal○Exercise: Promises and Async Await○Demo: Offline API Coordination○Exercise: Async API Simulation○Demo: Partial Results Bulletin○Project: Resilient Awards Feed○Demo: Retry a Local Delivery○Project: Reliable Score Delivery✦Module Quiz

Demo: Charging Rack Restock Report

The stage crew keeps an ordered list of charging racks. Each inner array is a [label, units] pair. Find the racks below five units so they can be refilled first.

javascript
const racks = [["East", 4], ["West", 8], ["Balcony", 1]];
const target = 5;
const lowRacks = racks.filter((rack) => rack[1] < target);
const fewestFirst = lowRacks.slice().sort((a, b) => a[1] - b[1]);
const labels = fewestFirst.map((rack) => rack[0]);
const unitsToAdd = fewestFirst.reduce((total, rack) => total + target - rack[1], 0);
console.log(`${labels.join(", ")} | ${unitsToAdd}`);

filter() keeps only racks below the target. The numeric comparator sorts by quantity rather than converting quantities to strings. slice() copies the filtered array before sort() mutates it; the original racks list stays in its original order. reduce() starts at zero, so it also handles a day when nothing needs refilling.

Checkpoint

Run the example and check that Balcony comes before East and that their deficits add to five. The next lesson transfers this pattern to a different stock list; it does not require objects or a web page.