forked from FINAKON/HelpProject
1. Initial Commit - a boiler plate code and POC to realize the concept of context sensitive help 2. Frontend code written in ReactJS 3. Backend code written in Java, Spring Boot Framework 4. Frontend Start: pre-requisites : node, npm npm run dev ==> to start the frontend vite server 5. Backend Start: pre-requisites : java, mvn mvn spring-boot:run ==> to start the backend server 6. Visit http://localhost:5173/ for basic demo of help, press F1 in textboxes 7. Visit http://localhost:5173/editor and enter "admin123" to add/modify texts. Happy Coding !!! Thank you, Bhargava.
106 lines
4.1 KiB
Markdown
106 lines
4.1 KiB
Markdown
# EventEmitter3
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[](https://www.npmjs.com/package/eventemitter3)[](https://travis-ci.org/primus/eventemitter3)[](https://david-dm.org/primus/eventemitter3)[](https://coveralls.io/r/primus/eventemitter3?branch=master)[](https://webchat.freenode.net/?channels=primus)
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[](https://saucelabs.com/u/eventemitter3)
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EventEmitter3 is a high performance EventEmitter. It has been micro-optimized
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for various of code paths making this, one of, if not the fastest EventEmitter
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available for Node.js and browsers. The module is API compatible with the
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EventEmitter that ships by default with Node.js but there are some slight
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differences:
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- Domain support has been removed.
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- We do not `throw` an error when you emit an `error` event and nobody is
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listening.
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- The `newListener` event is removed as the use-cases for this functionality are
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really just edge cases.
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- No `setMaxListeners` and its pointless memory leak warnings. If you want to
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add `end` listeners you should be able to do that without modules complaining.
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- No `listenerCount` method. Use `EE.listeners(event).length` instead.
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- Support for custom context for events so there is no need to use `fn.bind`.
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- The `listeners` method can do existence checking instead of returning only
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arrays.
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- The `removeListener` method removes all matching listeners, not only the
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first.
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It's a drop in replacement for existing EventEmitters, but just faster. Free
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performance, who wouldn't want that? The EventEmitter is written in EcmaScript 3
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so it will work in the oldest browsers and node versions that you need to
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support.
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## Installation
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```bash
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$ npm install --save eventemitter3 # npm
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$ component install primus/eventemitter3 # Component
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$ bower install eventemitter3 # Bower
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```
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## Usage
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After installation the only thing you need to do is require the module:
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```js
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var EventEmitter = require('eventemitter3');
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```
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And you're ready to create your own EventEmitter instances. For the API
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documentation, please follow the official Node.js documentation:
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http://nodejs.org/api/events.html
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### Contextual emits
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We've upgraded the API of the `EventEmitter.on`, `EventEmitter.once` and
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`EventEmitter.removeListener` to accept an extra argument which is the `context`
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or `this` value that should be set for the emitted events. This means you no
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longer have the overhead of an event that required `fn.bind` in order to get a
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custom `this` value.
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```js
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var EE = new EventEmitter()
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, context = { foo: 'bar' };
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function emitted() {
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console.log(this === context); // true
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}
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EE.once('event-name', emitted, context);
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EE.on('another-event', emitted, context);
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EE.removeListener('another-event', emitted, context);
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```
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### Existence
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To check if there is already a listener for a given event you can supply the
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`listeners` method with an extra boolean argument. This will transform the
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output from an array, to a boolean value which indicates if there are listeners
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in place for the given event:
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```js
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var EE = new EventEmitter();
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EE.once('event-name', function () {});
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EE.on('another-event', function () {});
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EE.listeners('event-name', true); // returns true
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EE.listeners('unknown-name', true); // returns false
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```
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### Tests and benchmarks
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This module is well tested. You can run:
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- `npm test` to run the tests under Node.js.
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- `npm run test-browser` to run the tests in real browsers via Sauce Labs.
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We also have a set of benchmarks to compare EventEmitter3 with some available
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alternatives. To run the benchmarks run `npm run benchmark`.
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Tests and benchmarks are not included in the npm package. If you want to play
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with them you have to clone the GitHub repository.
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## License
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[MIT](LICENSE)
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