Globe observer

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The GLOBE Observer App. The GLOBE Zika Education and Prevention project utilizes the GLOBE Program app, GLOBE Observer, to collect mosquito larvae observations in The GLOBE Observer website has been designed to support those who participate in The GLOBE Program primarily through the GLOBE Observer app. On the GLOBE Observer

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GLOBE Observer - GLOBE Observer - GLOBE.gov

LikeBillboard -Rolling Stone -Sourcing Journal -Sportico -Variety -WWDThe Epoch Times sites like (opt-in to custom sites for br|cz|de|fr|jp|ro sites)Epoch.org.il -The Epoch TimesLocal USA newsAlbuquerque Journal -CNN -Fox News -Honolulu Star-Advertiser -Las Vegas Review-Journal -Los Angeles Times -Mountain View Voice -New York Magazine (+ Curbed, Grub Street, The Cut & Vulture) -Newsday -Palo Alto Online -Pittsburgh Post Gazette -Star Tribune -Tampa Bay Times -The Baltimore Banner -The Boston Globe -The Columbian -The Dallas Morning News -The Hill -The New York Sun -The Salt Lake Tribune -The San Francisco Standard -The Seattle Times -The Philadelphia InquirerUSA TodayGrouped in options:Advance Local sites likeAL/Alabama -MLive/Michigan -NJ/New Jersey -Staten Island Advance -The Express-Times -The Oregonian -The Patriot-News -The Plain Dealer -The Post-Standard -The RepublicanCNHI Group sites (opt-in to custom sites)Forum Communications sites (opt-in to custom sites)Gannett Group (local USA Today) sites like (opt-in to custom sites for unlisted)Austin American-Statesman -Democrat and Chronicle -Detroit Free Press -Knoxville News Sentinel -Memphis Commercial Appeal -Milwaukee Journal Sentinel -The Arizona Republic -The Cincinnati Enquirer -The Columbus Dispatch -The Courier-Journal -The Des Moines Register -The Detroit News -The Florida Times-Union -The Indianapolis Star -The News-Press -The Oklahoman -The Record (North Jersey) -The TennesseanHearst Communications (newspapers) sites like (opt-in to custom sites for unlisted)Albany Times Union -Connecticut Post -Houston Chronicle -New Haven Register -San Antonio Express-News -San Francisco ChronicleLee Enterprises Group sites like (opt-in to custom sites for unlisted)Arizona Daily Star -Lincoln Journal Star -Omaha World-Herald -Richmond Times-Dispatch -St. Louis Post-Dispatch -The Buffalo News -The Times of Northwest Indiana -Tulsa World -Wisconsin State Journal -Winston-Salem JournalMaine Trust sites (opt-in to custom sites)McClatchy Group sites like (opt-in to custom sites for unlisted)Belleville News-Democrat -El Nuevo Herald -Fort Worth Star-Telegram -Lexington Herald-Leader -McClatchy DC -Miami Herald -The Charlotte Observer -The Fresno Bee -The Kansas City Star -The News & Observer -The Sacramento Bee Explorers have been navigating the globe for centuries. Circumnavigation refers to traveling around something like the continent or any astrological body. The circumnavigation distance should encompass going around the object around the great circle.The great circle distance on earth is about 40,000km which is the minimum distance required to circumnavigate the globe. The most efficient way of circumnavigating the earth is by passing through at least one pair of antipodal points and covering the minimum distance of the equator and spending equal time in both the northern and southern hemispheres. 15. Magellan-Elcano Expedition Magellan Elcano expedition was a Spanish voyage and the first to circumnavigate the world under the command of Ferdinand Magellan, a Portuguese explorer in search of a maritime route to Spice Island, Indonesia. Although Ferdinand was killed en route in the present day the Philippines, his crew comprising of 18 members completed the round the world voyage under the command of Sebastián Elcano on September 6, 1522. 14. Francis Drake Francis Drake, a renowned pirate of slaving voyages in the 16th century, was sent to South America in 1577 by Queen Elizabeth II to intercept the gold, silver, and jewelry that the Spanish were shipping to Spain across the Isthmus of Panama.Drake was successful in capturing twenty-six tons of silver, half a ton of gold, and pieces of jewelry. Since he could not sail back along South America, he proceeded to north California traversing through North and South America, Asia, Africa and returning to Europe in 1580 becoming the second person to circumnavigate the globe. 13. Martín Ignacio de Loyola Martín Ignacio was a renowned missionary in India and China, who circumnavigated the globe twice in his lifetime. His first circumnavigation was made in a westerly direction from 1582-1584 from the Canary Islands while the second was made in an easterly direction between 1585 and 1589. On both accounts, Ignacio took advantage of the crown of Phillip II of Spain which united Spain and Portugal. 12. Pedro Cubero Pedro was an ordained Spanish priest who enjoyed traveling the world in pursuit of his missionary work. In 1670. Pedro embarked on a journey to East Asia that eventually led him to circumnavigate the globe through the eastern direction. Unlike his predecessors who circumnavigated the globe through marine voyages, Pedro embarked on a land voyage through Western and Eastern Europe, Western and Central Asia and North America. 11. Giovanni Francesco Gemelli Careri Francesco Careri was a famous 17th-century Italian adventurer and traveler. He undertook an around-the-world trip through land and water in five years by securing passage in trade ships. His trip, which was mainly done for pleasure rather than profit, was recorded in the sixth volume of the Giro Del Mondo, which gives detailed accounts of all the countries he visited. 10. William Dampier William Dampier was a great English explorer who explored modern day Australia and became the first person to circumnavigate the world three times. As a buccaneer, sea captain, author and scientific observer, William traveled

Family Science with GLOBE Observer - GLOBE Observer - GLOBE

That implements the Subject interface: // Subjectclass Store implements Subject {} Next, initialize the Subject’s state in the Store class. The subject’s observers will react to changes to this state. In this case, the state is a number, and the observers will react to an increase in the number: // Subject stateprivate numberOfProducts: number; Next, initialize an array of observers. This array is how you'll keep track of the observers: // initializing observersprivate observers: Observer[] = []; You might find some implementations of the observer pattern using a Set data structure in place of an array to keep track of the observer. Using a Set will ensure that the same observer won’t appear twice. If you want to use an array instead, you should check for duplicate observers in your attach method. Next, you should implement the Subject’s methods—attach, detach, and notify/update—in your concrete class. To implement the attach method, first check if the observer is already attached and throw an error if it is. Otherwise, add the observer to the array using the JavaScript array method, push: // Attaching Observer(s)attachObserver(observer: Observer): void { // Check if the observer has already been attached const observerExists = this.observers.includes(observer); if (observerExists) { throw new Error('Observer has already been subscribed '); } // Add a new observer this.observers.push(observer);} Next, implement your detach method by finding the index and removing it from the array using the JavaScript splice method. There can be scenarios where the observer you are trying to detach has already been detached or was not subscribed in the first place. You should handle these scenarios by adding a conditional statement to check if the observer is in the array or the set as the case may be. // Detaching Observer(s)detachObserver(observer: Observer): void { console.log(`Detaching observer ${JSON.stringify(observer)}`); const observerIndex = this.observers.indexOf(observer); if. The GLOBE Observer App. The GLOBE Zika Education and Prevention project utilizes the GLOBE Program app, GLOBE Observer, to collect mosquito larvae observations in The GLOBE Observer website has been designed to support those who participate in The GLOBE Program primarily through the GLOBE Observer app. On the GLOBE Observer

Do GLOBE Observer - GLOBE Observer - GLOBE.gov

A design pattern is a template that solves a commonly recurring problem in software design. The observer pattern, also known as the publish-subscribe pattern, is a behavioral pattern. It allows you to notify multiple objects or subscribers about any event that is published in the object they’re observing. Here you will learn how to implement the observer design pattern in TypeScript. The Observer Pattern The observer pattern works by defining a one-to-many relationship between the publisher and its subscribers. When an event occurs in the publisher, it will notify all subscribers to that event. One widespread example of this pattern is JavaScript event listeners. For context, assume you’re building an inventory tracker that keeps track of the number of products in your store. In this case, your store is the subject/publisher, and your inventory is the observer/subscriber. Using the observer design pattern would be optimal in this situation. In the observer design pattern, your subject class must implement three methods: An attach method. This method adds an observer to the subject. A detach method. This method removes an observer from a subject. A notify/update method. This method notifies the subject’s observers when the state changes in the subject. Your observer class must implement one method, the update method. This method reacts when there’s a change in its subject’s state. Implementing the Subject and Observer Classes The first step to implementing this pattern is to create interfaces for the subject and observer class, to ensure that they implement the correct methods: // Subject/Publisher Interfaceinterface Subject { attachObserver(observer: Observer): void; detachObserver(observer: Observer): void; notifyObserver(): void;} // Observer/Subscriber Interfaceinterface Observer { update(subject: Subject): void;} The interfaces in the code block above define the methods your concrete classes must implement. A Concrete Subject Class The next step is to implement a concrete subject class (observerIndex === -1) { throw new Error('Observer does not exist'); } this.observers.splice(observerIndex, 1); console.log('Observer detached...');} Next, implement your notify/update method by looping over your list of observers and calling the update method of each one: // Notifying ObserversnotifyObserver(): void { console.log('Notifying observers...'); for (const observer of this.observers) { observer.update(this); }} Finally, for the Subject class, implement a method that manipulates the state and then notifies the observers of the change by calling their notify/update method. This example is a simplification of how a subject might perform an action and then inform observers: // Changing state and notifying observersnewProduct(products: number): void { this.numberOfProducts += products; console.log('New product added to the store'); this.notifyObserver();} Concrete Observer Classes Create an observer class or classes, to subscribe to the publisher. Each observer class must implement the Observer interface. The observer classes will implement a notify/update method which only the subject they are observing should call. This method should contain all the business logic you need to run in response to a change in the subject’s state: // Concrete Observer 1class Inventory implements Observer { update(): void { console.log('New product added to the store, updating inventory...'); // Actual business logic goes here... }} // Concrete Observer 2class Customer implements Observer { update(): void { console.log('New product added to the store, I have to go check it out...'); // Actual business logic goes here... }} Using the Observer Pattern To use this pattern, instantiate the concrete subject and observer classes. Once you’ve done so, call the Subject’s attach method and pass the Observer instance as an argument. In response, the subject will add that instance to its list of observers: // Instantiating Subject and Observerconst store = new Store();const inventory = new Inventory();const customer = new Customer() // Subscribing objects to publisherstore.attachObserver(inventory);store.attachObserver(customer);// Changing subject statestore.newProduct(30); This code

Taking Mosquito Habitat Observations - GLOBE Observer - GLOBE

In Ford’s world.” — The New York Observer“Brutally honest … Brinkley has written a perfectly sound history, briskly paced, and packed with facts, clearly written.” — Forbes“Wheels for the World … pulls the reader through some 800 pages with clever character sketches, well-informed accounts of automobile engineering, and a balanced view of Ford’s role in American society … a compelling account of the company’s incredible success story.” — The Boston Globe “Well-written, thoroughly researched, fair-minded business histories are as rare as they are valuable. This book qualifies on all those counts … composed with cool sympathy.” — St. Louis Post-Dispatch“To a T: Douglas Brinkley’s Henry Ford comes fully loaded, capturing the dichotomy of the farm boy who unleashed unprecedented industrial power. … Brinkley is such a fine descriptive writer that even the uninitiated may enjoy the design detail.” — The Times-Picayune (New Orleans) “An amazing story … Douglas Brinkley didn’t get mired in nuts and bolts in Wheels for the World, his social history of Ford Motor Company, because he knew this story was about more than Tin Lizzies and Mustangs. Instead he wrote the epic of the man and the company that shaped the modern world. This story has twists and turns enough to handily supplant the two or three novels you might have read. … A classic story of people and power.” — The Oregonian“This definitive recounting of the Ford Motor Company’s first one hundred years is business history at its very best.” — Richmond Times-Dispatch“A fascinating epic

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Like plain JS objects.import { observable } from '@nx-js/observer-util';const counter = observable({ num: 0 });// observables behave like plain JS objectscounter.num = 12;ReactionsReactions are functions, which use observables. They can be created with the observe function and they are automatically executed whenever the observables - used by them - change.Vanilla JavaScript console.log(counter.num));// this calls countLogger and logs 1counter.num++;">import { observable, observe } from '@nx-js/observer-util';const counter = observable({ num: 0 });const countLogger = observe(() => console.log(counter.num));// this calls countLogger and logs 1counter.num++;React Component {counter.num});">import { store, view } from 'react-easy-state';// this is an observable storeconst counter = store({ num: 0, up() { this.num++; }});// this is a reactive component, which re-renders whenever counter.num changesconst UserComp = view(() => div onClick={counter.up}>{counter.num}div>);Preact Component{store.title} }}">import { observer } from "preact-nx-observer";let store = observable({ title: "This is foo's data"});@observer // Component will now re-render whenever store.title changes.class Foo extends Component { render() { return h1>{store.title}h1> }}More examplesDynamic properties console.log(profile.name));// logs 'Bob'profile.name = 'Bob';">import { observable, observe } from '@nx-js/observer-util';const profile = observable();observe(() => console.log(profile.name));// logs 'Bob'profile.name = 'Bob';Nested properties console.log(`${person.name.first} ${person.name.last}`));// logs 'Bob Smith'person.name.first = 'Bob';">import { observable, observe } from '@nx-js/observer-util';const person = observable({ name: { first: 'John', last: 'Smith' }, age: 22});observe(() => console.log(`${person.name.first} ${person.name.last}`));// logs 'Bob Smith'person.name.first = 'Bob';Getter properties console.log(person.name));// logs 'Ann Smith'person.firstName = 'Ann';">import { observable, observe } from '@nx-js/observer-util';const person = observable({ firstName: 'Bob', lastName: 'Smith', get name() { return `${this.firstName} ${this.lastName}`; }});observe(() => console.log(person.name));// logs 'Ann Smith'person.firstName = 'Ann';Conditionals { if (person.gender === 'male') { console.log(`Mr. ${person.name}`); } else { console.log(`Ms. ${person.name}`); }});// logs 'Ms. Potato'person.gender = 'female';">import { observable, observe } from '@nx-js/observer-util';const person = observable({ gender: 'male', name: 'Potato'});observe(() => { if (person.gender === 'male') { console.log(`Mr. ${person.name}`); } else { console.log(`Ms. ${person.name}`); }});// logs 'Ms. Potato'person.gender = 'female';Arrays console.log(users.join(', ')));// logs 'Bob'users.push('Bob');// logs 'Bob, John'users.push('John');//. The GLOBE Observer App. The GLOBE Zika Education and Prevention project utilizes the GLOBE Program app, GLOBE Observer, to collect mosquito larvae observations in The GLOBE Observer website has been designed to support those who participate in The GLOBE Program primarily through the GLOBE Observer app. On the GLOBE Observer

The GLOBE Program's Globe Observer App

"This unarmed observation drone looks precisely like what it is: an eye in the sky. Deployed to scout unexplored terrain or enemy territory, the observer serves as an invaluable tactical reconnaissance tool for protoss commanders. Heads-up knowledge of enemy movements and logistics often proves to be the difference-maker in an otherwise evenly balanced encounter."The observer is a small, stealthy robotic protoss reconnaissance unit.Overview[] An observer during the Great War The observer is a small aerospace drone used to survey space and record events for analysis in protoss archives.[1][2] The observer's primary means of locomotion is a discrete thruster that creates a gravity field, while energy-sheathed "fins" manipulate said field to generate lift and propulsion. Without modifications, the observer can adequately travel from one point to another, but is hard pressed to outrun pursuers—unless outfitted with a set of gravitic boosters.[3] Older observers had a different stabilizer configuring that, while equally effective, gave a more imposing aspect, and some phase-smiths stated this older configuration improved performance.[4]Observers are fragile craft, and possess very little armor. Their speed and cloaking abilities give them a measure of survivability, but if detected, observers are usually an easy kill unless they withdraw quickly.[5] An observer approaches a world Observers may be equipped for warp space travel and deployed for deep-space exploration.[6] Units used for this purpose often lack defensive systems.[2] They may re-enter real space within planetary atmospheres and transmit data in real-time over interstellar distances. In addition observers may drop navigational beacons as homing devices.[6] A Tal'darim observer By 2506, observers were in use by the Tal'darim.[7] The most cunning ascendants make extensive use of observers to spy on Slayn's enemies, or on each other.After their activation, the Purifiers especially prized their observers, which soon became a favored construct of Talandar.The Ihan-rii utilized observers for millennia, using them to observe the other protoss sects and zerg without danger of being discovered.[4]Detection[] An observer The complex but sensitive sensor[2] matrix[3] is power intensive,[2] but can collect massive amounts of data in a short amount of time. The critical data gathered by observers has turned the tide of battle numerous times.[4]The observer may detect cloaked and concealed objects.[2] This includes burrowers and all types of camouflage or stealth systems.[3] It is sophisticated enough to even detect zerg spores within terrans.[8][9] It is comprised of complex arrays of self-focusing lenses, powered by psionic lattices, which allow the observer to analyze the battlefield from its vantage point in the sky.[3] A sensor array upgrade significantly increases the observer's sight range and sensitivity.[5] These properties make the observer a valuable auxiliary on the battlefield.[2]Stealth[] The current observer design Observers intended for combat zones are equipped with a defensive micro-cloaking field.

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LikeBillboard -Rolling Stone -Sourcing Journal -Sportico -Variety -WWDThe Epoch Times sites like (opt-in to custom sites for br|cz|de|fr|jp|ro sites)Epoch.org.il -The Epoch TimesLocal USA newsAlbuquerque Journal -CNN -Fox News -Honolulu Star-Advertiser -Las Vegas Review-Journal -Los Angeles Times -Mountain View Voice -New York Magazine (+ Curbed, Grub Street, The Cut & Vulture) -Newsday -Palo Alto Online -Pittsburgh Post Gazette -Star Tribune -Tampa Bay Times -The Baltimore Banner -The Boston Globe -The Columbian -The Dallas Morning News -The Hill -The New York Sun -The Salt Lake Tribune -The San Francisco Standard -The Seattle Times -The Philadelphia InquirerUSA TodayGrouped in options:Advance Local sites likeAL/Alabama -MLive/Michigan -NJ/New Jersey -Staten Island Advance -The Express-Times -The Oregonian -The Patriot-News -The Plain Dealer -The Post-Standard -The RepublicanCNHI Group sites (opt-in to custom sites)Forum Communications sites (opt-in to custom sites)Gannett Group (local USA Today) sites like (opt-in to custom sites for unlisted)Austin American-Statesman -Democrat and Chronicle -Detroit Free Press -Knoxville News Sentinel -Memphis Commercial Appeal -Milwaukee Journal Sentinel -The Arizona Republic -The Cincinnati Enquirer -The Columbus Dispatch -The Courier-Journal -The Des Moines Register -The Detroit News -The Florida Times-Union -The Indianapolis Star -The News-Press -The Oklahoman -The Record (North Jersey) -The TennesseanHearst Communications (newspapers) sites like (opt-in to custom sites for unlisted)Albany Times Union -Connecticut Post -Houston Chronicle -New Haven Register -San Antonio Express-News -San Francisco ChronicleLee Enterprises Group sites like (opt-in to custom sites for unlisted)Arizona Daily Star -Lincoln Journal Star -Omaha World-Herald -Richmond Times-Dispatch -St. Louis Post-Dispatch -The Buffalo News -The Times of Northwest Indiana -Tulsa World -Wisconsin State Journal -Winston-Salem JournalMaine Trust sites (opt-in to custom sites)McClatchy Group sites like (opt-in to custom sites for unlisted)Belleville News-Democrat -El Nuevo Herald -Fort Worth Star-Telegram -Lexington Herald-Leader -McClatchy DC -Miami Herald -The Charlotte Observer -The Fresno Bee -The Kansas City Star -The News & Observer -The Sacramento Bee

2025-04-18
User6020

Explorers have been navigating the globe for centuries. Circumnavigation refers to traveling around something like the continent or any astrological body. The circumnavigation distance should encompass going around the object around the great circle.The great circle distance on earth is about 40,000km which is the minimum distance required to circumnavigate the globe. The most efficient way of circumnavigating the earth is by passing through at least one pair of antipodal points and covering the minimum distance of the equator and spending equal time in both the northern and southern hemispheres. 15. Magellan-Elcano Expedition Magellan Elcano expedition was a Spanish voyage and the first to circumnavigate the world under the command of Ferdinand Magellan, a Portuguese explorer in search of a maritime route to Spice Island, Indonesia. Although Ferdinand was killed en route in the present day the Philippines, his crew comprising of 18 members completed the round the world voyage under the command of Sebastián Elcano on September 6, 1522. 14. Francis Drake Francis Drake, a renowned pirate of slaving voyages in the 16th century, was sent to South America in 1577 by Queen Elizabeth II to intercept the gold, silver, and jewelry that the Spanish were shipping to Spain across the Isthmus of Panama.Drake was successful in capturing twenty-six tons of silver, half a ton of gold, and pieces of jewelry. Since he could not sail back along South America, he proceeded to north California traversing through North and South America, Asia, Africa and returning to Europe in 1580 becoming the second person to circumnavigate the globe. 13. Martín Ignacio de Loyola Martín Ignacio was a renowned missionary in India and China, who circumnavigated the globe twice in his lifetime. His first circumnavigation was made in a westerly direction from 1582-1584 from the Canary Islands while the second was made in an easterly direction between 1585 and 1589. On both accounts, Ignacio took advantage of the crown of Phillip II of Spain which united Spain and Portugal. 12. Pedro Cubero Pedro was an ordained Spanish priest who enjoyed traveling the world in pursuit of his missionary work. In 1670. Pedro embarked on a journey to East Asia that eventually led him to circumnavigate the globe through the eastern direction. Unlike his predecessors who circumnavigated the globe through marine voyages, Pedro embarked on a land voyage through Western and Eastern Europe, Western and Central Asia and North America. 11. Giovanni Francesco Gemelli Careri Francesco Careri was a famous 17th-century Italian adventurer and traveler. He undertook an around-the-world trip through land and water in five years by securing passage in trade ships. His trip, which was mainly done for pleasure rather than profit, was recorded in the sixth volume of the Giro Del Mondo, which gives detailed accounts of all the countries he visited. 10. William Dampier William Dampier was a great English explorer who explored modern day Australia and became the first person to circumnavigate the world three times. As a buccaneer, sea captain, author and scientific observer, William traveled

2025-03-25
User9129

That implements the Subject interface: // Subjectclass Store implements Subject {} Next, initialize the Subject’s state in the Store class. The subject’s observers will react to changes to this state. In this case, the state is a number, and the observers will react to an increase in the number: // Subject stateprivate numberOfProducts: number; Next, initialize an array of observers. This array is how you'll keep track of the observers: // initializing observersprivate observers: Observer[] = []; You might find some implementations of the observer pattern using a Set data structure in place of an array to keep track of the observer. Using a Set will ensure that the same observer won’t appear twice. If you want to use an array instead, you should check for duplicate observers in your attach method. Next, you should implement the Subject’s methods—attach, detach, and notify/update—in your concrete class. To implement the attach method, first check if the observer is already attached and throw an error if it is. Otherwise, add the observer to the array using the JavaScript array method, push: // Attaching Observer(s)attachObserver(observer: Observer): void { // Check if the observer has already been attached const observerExists = this.observers.includes(observer); if (observerExists) { throw new Error('Observer has already been subscribed '); } // Add a new observer this.observers.push(observer);} Next, implement your detach method by finding the index and removing it from the array using the JavaScript splice method. There can be scenarios where the observer you are trying to detach has already been detached or was not subscribed in the first place. You should handle these scenarios by adding a conditional statement to check if the observer is in the array or the set as the case may be. // Detaching Observer(s)detachObserver(observer: Observer): void { console.log(`Detaching observer ${JSON.stringify(observer)}`); const observerIndex = this.observers.indexOf(observer); if

2025-04-19
User6674

A design pattern is a template that solves a commonly recurring problem in software design. The observer pattern, also known as the publish-subscribe pattern, is a behavioral pattern. It allows you to notify multiple objects or subscribers about any event that is published in the object they’re observing. Here you will learn how to implement the observer design pattern in TypeScript. The Observer Pattern The observer pattern works by defining a one-to-many relationship between the publisher and its subscribers. When an event occurs in the publisher, it will notify all subscribers to that event. One widespread example of this pattern is JavaScript event listeners. For context, assume you’re building an inventory tracker that keeps track of the number of products in your store. In this case, your store is the subject/publisher, and your inventory is the observer/subscriber. Using the observer design pattern would be optimal in this situation. In the observer design pattern, your subject class must implement three methods: An attach method. This method adds an observer to the subject. A detach method. This method removes an observer from a subject. A notify/update method. This method notifies the subject’s observers when the state changes in the subject. Your observer class must implement one method, the update method. This method reacts when there’s a change in its subject’s state. Implementing the Subject and Observer Classes The first step to implementing this pattern is to create interfaces for the subject and observer class, to ensure that they implement the correct methods: // Subject/Publisher Interfaceinterface Subject { attachObserver(observer: Observer): void; detachObserver(observer: Observer): void; notifyObserver(): void;} // Observer/Subscriber Interfaceinterface Observer { update(subject: Subject): void;} The interfaces in the code block above define the methods your concrete classes must implement. A Concrete Subject Class The next step is to implement a concrete subject class

2025-04-13
User6950

(observerIndex === -1) { throw new Error('Observer does not exist'); } this.observers.splice(observerIndex, 1); console.log('Observer detached...');} Next, implement your notify/update method by looping over your list of observers and calling the update method of each one: // Notifying ObserversnotifyObserver(): void { console.log('Notifying observers...'); for (const observer of this.observers) { observer.update(this); }} Finally, for the Subject class, implement a method that manipulates the state and then notifies the observers of the change by calling their notify/update method. This example is a simplification of how a subject might perform an action and then inform observers: // Changing state and notifying observersnewProduct(products: number): void { this.numberOfProducts += products; console.log('New product added to the store'); this.notifyObserver();} Concrete Observer Classes Create an observer class or classes, to subscribe to the publisher. Each observer class must implement the Observer interface. The observer classes will implement a notify/update method which only the subject they are observing should call. This method should contain all the business logic you need to run in response to a change in the subject’s state: // Concrete Observer 1class Inventory implements Observer { update(): void { console.log('New product added to the store, updating inventory...'); // Actual business logic goes here... }} // Concrete Observer 2class Customer implements Observer { update(): void { console.log('New product added to the store, I have to go check it out...'); // Actual business logic goes here... }} Using the Observer Pattern To use this pattern, instantiate the concrete subject and observer classes. Once you’ve done so, call the Subject’s attach method and pass the Observer instance as an argument. In response, the subject will add that instance to its list of observers: // Instantiating Subject and Observerconst store = new Store();const inventory = new Inventory();const customer = new Customer() // Subscribing objects to publisherstore.attachObserver(inventory);store.attachObserver(customer);// Changing subject statestore.newProduct(30); This code

2025-04-18

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