Initial

.babelrc

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+{
+	"presets": ["@babel/env", "@babel/typescript"],
+	"plugins": ["@babel/proposal-class-properties", "@babel/proposal-object-rest-spread"]
+}

.gitignore

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+lib
+dist
+node_modules

LICENSE

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+MIT License
+
+Copyright (c) 2021 John Michael Manlupig
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# @avidian/events
+
+A pub/sub library for handling events.
+
+## Installation
+
+NPM
+
+```sh
+npm install @avidian/events
+```
+
+Yarn
+
+```sh
+yarn add @avidian/events
+```
+
+## Usage
+
+```javascript
+import { Manager } from '@avidian/events';
+
+const manager = new Manager();
+
+// listen to events
+const key = manager.on('my_event_key', (value) => {
+    console.log(value);
+}); // or manager.listen(name, callback)
+
+// dispatch values to events
+manager.dispatch('my_event_key', 'value');
+
+// unlisten specific key to events
+manager.off(key); // or manager.unlisten(key)
+
+// clear all listeners
+manager.clear();
+
+```
+
+## License
+
+[MIT License](https://github.com/avidianity/events/blob/master/LICENSE)

package.json

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+{
+	"name": "@avidian/events",
+	"version": "1.0.0",
+	"description": "A pub/sub library for handling events.",
+	"main": "lib/index.js",
+	"repository": "https://github.com/avidianity/events",
+	"author": "John Michael Manlupig",
+	"types": "types/index.d.ts",
+	"scripts": {
+		"type-check": "tsc --noEmit",
+		"type-check:watch": "npm run type-check -- --watch",
+		"clean": "rm -rf dist && rm -rf types",
+		"build": "npm run clean && npm run build:types && npm run build:js",
+		"build:types": "tsc --emitDeclarationOnly",
+		"build:js": "babel src --out-dir lib --extensions \".ts,.tsx\" --source-maps inline",
+		"test": "jest ts-node/register tests/*.test.ts"
+	},
+	"license": "MIT",
+	"private": false,
+	"devDependencies": {
+		"@babel/cli": "^7.14.8",
+		"@babel/core": "^7.15.0",
+		"@babel/plugin-proposal-class-properties": "^7.14.5",
+		"@babel/preset-env": "^7.15.0",
+		"@babel/preset-typescript": "^7.15.0",
+		"@types/jest": "^27.0.1",
+		"@types/uuid": "^8.3.1",
+		"jest": "^27.0.6",
+		"typescript": "^4.3.5"
+	},
+	"dependencies": {
+		"uuid": "^8.3.2"
+	}
+}

src/Key.ts

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+import { v4 } from 'uuid';
+
+export class Key {
+	protected id: string;
+	protected name: string;
+
+	constructor(name: string) {
+		this.id = v4();
+		this.name = name;
+	}
+
+	getID() {
+		return this.id;
+	}
+
+	getName() {
+		return this.name;
+	}
+
+	toString() {
+		return `'${this.id} - ${this.name}'`;
+	}
+}

src/Manager.ts

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+import { Key } from './Key';
+import { Observer } from './Observer';
+
+type Observers = {
+	[key: string]: Observer[];
+};
+
+export class Manager {
+	protected observers: Observers = {};
+
+	getObservers(): Observers {
+		return { ...this.observers };
+	}
+
+	on<T = any>(key: string, callback: (value: T) => void) {
+		return this.listen<T>(key, callback);
+	}
+
+	off(key: Key) {
+		return this.unlisten(key);
+	}
+
+	clear() {
+		for (const key in this.observers) {
+			this.observers[key] = [];
+		}
+
+		return this;
+	}
+
+	listen<T = any>(key: string, callback: (value: T) => void) {
+		if (!(key in this.observers)) {
+			this.observers[key] = [];
+		}
+
+		const handle = new Key(key);
+		this.observers[key].unshift(new Observer(handle, callback));
+
+		return handle;
+	}
+
+	unlisten(key: Key) {
+		const name = key.getName();
+		const id = key.getID();
+
+		if (!(name in this.observers)) {
+			return;
+		}
+
+		const index = this.observers[name].findIndex((observer) => observer.getKey().getID() === id);
+
+		if (index >= 0) {
+			this.observers[name].splice(index, 1);
+		}
+	}
+
+	dispatch(name: string, value?: any) {
+		if (!(name in this.observers)) {
+			return this;
+		}
+
+		this.observers[name].forEach((observer) => observer.execute(value));
+		return this;
+	}
+}

src/Observer.ts

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+import { Key } from './Key';
+
+export class Observer {
+	protected key: Key;
+	protected callback: Function;
+
+	constructor(key: Key, callback: Function) {
+		this.key = key;
+		this.callback = callback;
+	}
+
+	execute(value: any) {
+		this.callback(value);
+	}
+
+	getKey() {
+		return this.key;
+	}
+}

src/index.ts

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+export { Manager } from './Manager';

tests/index.test.ts

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+import { Manager } from '../src';
+import { Key } from '../src/Key';
+
+describe('manager works as a pub/sub client', () => {
+	it('creates a key for a listener', () => {
+		const manager = new Manager();
+
+		const key = manager.listen('key', () => {});
+
+		expect(key).toBeInstanceOf(Key);
+	});
+
+	it('removes a key for a listener', () => {
+		const manager = new Manager();
+
+		const key = manager.listen('key', () => {});
+
+		manager.unlisten(key);
+
+		const exists = manager.getObservers()[key.getName()].find((k) => key.getID() === key.getID());
+
+		expect(exists).toBeUndefined();
+	});
+
+	it('dispatches values to listeners', () => {
+		return new Promise<void>((resolve, reject) => {
+			const manager = new Manager();
+
+			let handle: NodeJS.Timeout | null = null;
+
+			manager.listen('key', () => {
+				if (handle) {
+					clearTimeout(handle);
+				}
+				resolve();
+			});
+
+			manager.dispatch('key', null);
+
+			handle = setTimeout(reject, 1000);
+		});
+	});
+
+	it('does not dispatch values to listeners', () => {
+		return new Promise<void>((resolve, reject) => {
+			const manager = new Manager();
+
+			const key = manager.listen('key', reject);
+
+			manager.unlisten(key);
+
+			manager.dispatch('key', null);
+
+			resolve();
+		});
+	});
+});

tsconfig.json

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+{
+	"compilerOptions": {
+		/* Basic Options */
+		"target": "esnext" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */,
+		"module": "commonjs" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */,
+		// "lib": [],                             /* Specify library files to be included in the compilation. */
+		// "allowJs": true,                       /* Allow javascript files to be compiled. */
+		// "checkJs": true,                       /* Report errors in .js files. */
+		// "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
+		"declaration": true /* Generates corresponding '.d.ts' file. */,
+		// "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
+		// "sourceMap": true,                     /* Generates corresponding '.map' file. */
+		// "outFile": "./",                       /* Concatenate and emit output to single file. */
+		"outDir": "lib" /* Redirect output structure to the directory. */,
+		// "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
+		// "composite": true,                     /* Enable project compilation */
+		// "removeComments": true,                /* Do not emit comments to output. */
+		// "noEmit": true,                        /* Do not emit outputs. */
+		// "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
+		// "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
+		// "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
+
+		/* Strict Type-Checking Options */
+		"strict": true /* Enable all strict type-checking options. */,
+		// "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
+		// "strictNullChecks": true,              /* Enable strict null checks. */
+		// "strictFunctionTypes": true,           /* Enable strict checking of function types. */
+		// "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
+		// "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
+		// "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
+
+		/* Additional Checks */
+		// "noUnusedLocals": true,                /* Report errors on unused locals. */
+		// "noUnusedParameters": true,            /* Report errors on unused parameters. */
+		// "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
+		// "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
+
+		/* Module Resolution Options */
+		// "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
+		// "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
+		// "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
+		// "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
+		// "typeRoots": [],                       /* List of folders to include type definitions from. */
+		// "types": [],                           /* Type declaration files to be included in compilation. */
+		"allowSyntheticDefaultImports": true /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */,
+		"esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
+		// "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+
+		/* Source Map Options */
+		// "sourceRoot": "./",                    /* Specify the location where debugger should locate TypeScript files instead of source locations. */
+		// "mapRoot": "./",                       /* Specify the location where debugger should locate map files instead of generated locations. */
+		// "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
+		// "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
+
+		/* Experimental Options */
+		// "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
+		// "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
+
+		/* Advanced Options */
+		"declarationDir": "types" /* Output directory for generated declaration files. */,
+		"skipLibCheck": true /* Skip type checking of declaration files. */,
+		"forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */
+	},
+	"exclude": ["tests"]
+}

types/Key.d.ts

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+export declare class Key {
+    protected id: string;
+    protected name: string;
+    constructor(name: string);
+    getID(): string;
+    getName(): string;
+    toString(): string;
+}

types/Manager.d.ts

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+import { Key } from './Key';
+import { Observer } from './Observer';
+declare type Observers = {
+    [key: string]: Observer[];
+};
+export declare class Manager {
+    protected observers: Observers;
+    getObservers(): Observers;
+    on<T = any>(key: string, callback: (value: T) => void): Key;
+    off(key: Key): void;
+    listen<T = any>(key: string, callback: (value: T) => void): Key;
+    unlisten(key: Key): void;
+    dispatch(name: string, value?: any): this;
+}
+export {};

types/Observer.d.ts

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+import { Key } from './Key';
+export declare class Observer {
+    protected key: Key;
+    protected callback: Function;
+    constructor(key: Key, callback: Function);
+    execute(value: any): void;
+    getKey(): Key;
+}

types/index.d.ts

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+export { Manager } from './Manager';