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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

Exercise: Report Seat Reservation Results

Reserve workshop seats

The route demo sent either an error or a destination to one callback. A workshop reservation has another constraint: requests must be positive whole numbers no greater than the available seats.

reserveSeats(requested, available, callback) should invoke its callback once, synchronously. On success, send { reserved: requested, remaining: available - requested }; on failure send an Error with the message Invalid seat request and a null result. Do not return a result in place of calling the callback.

Worked example

A separate callback receives either an error or a value, once:

javascript
function checkBadge(id, callback) {
  if (!id) return callback(new Error("Missing badge"), null);
  callback(null, { badge: id });
}
checkBadge("B7", (error, result) => console.log(error, result.badge)); // null B7

Your Task

  1. Complete the valid-request path in reserveSeats: call the callback once with null error and a result containing reserved and remaining.
  2. Complete the invalid-request path: reject zero, negative, fractional, or over-capacity counts with new Error("Invalid seat request") and a null result, calling back once.
  3. Log Reserved 2 seats; 3 remain in a callback for 2 of 5 seats.
Hint 1
1 / 2
HINT 1

Reject non-integers, zero, negative numbers, and requests over the available seats.

HINT 2

Invoke callback(error, null) on failure and callback(null, result) on success.

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