event driven programming in node js
EventEmitter ee new EventEmitter. As the name implies a programming paradigm where the flow of the program is governed by events.
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Whenever the Node server starts it initializes the variables declares functions and then goes into the state where it waits for events.
. Thats why you need the callback - you need a way to tell NodeJS what to do next when you finally get the data. The first argument in the emit method is the event name. The events module is used to Create Emit and Handle events.
In our previous example createServer from the net module uses on under the hood. Once we start a Nodejs server it initializes the variables and functions and then listens for the occurrence of an event. Contrary to what some programmers think I heard it a couple of times Nodejs is NOT a web server.
As soon as Node starts its server it simply initiates its variables declares functions and then simply waits for the event to occur. Function f new SpecialFunction. Event-Driven Programming is a term that is simply used when referring to the flow of events in either a click load and so forth.
Here is some psuedo-code to demonstrate my idea of event-driven programming. The other statements below the if block will be executed immediately once event registration is completed by nodejs. EDP is very imperative when it comes to todays most common programming languages like the java and the c.
In this analogy the event will be fired once when Node is ready to call the callback and the callback acts as the event handler. Any event-driven module in Nodejs extends a root class named EventEmitter. We have return statement outside the end event like below redirect resstatusCode302.
Call me when youre ready Node. It is capable of supporting concurrency through the idea of call backs and events. As being threaded they make use of async function calls.
Event-Driven Programming is a logical pattern that we can choose to confine our programming within to avoid issues of complexity and collision. Event-Driven programming is a core concept behind nodejs which is manifested by the implementation of the Events module. Event Loop in Nodejs is a single threaded application.
2 There is nothing inherently bad about callback hell other than it is hard to read. In practice it means that applications act on events. In addition all event properties and methods are an instance of an EventEmitter object.
EventEmitter in Nodejs has two fundamental methods. Node JS is known as an event-driven programming language therefore it is very fast and concurrent as compared to the other technologies. Use the instance of EventEmitter class to implement the emit method which fires an event called messageLogged in the code below.
It means as soon as Node starts its server it simply initiates its variables declares functions and then simply waits for event to occur. Instead its a JavaScript runtime environment. Popular Course in this category.
Lets explore this basic form first. The execution order of these two events is handled internally by nodejs. The events module is used to Create Emit and Handle events.
This process is called the event loop. Nodejs uses event driven programming. To be able to access these properties and methods create an EventEmitter object.
If you want to draw a parallel with the browser you can think of EventEmitter as of any HTML element able to emit events. Event-Driven Programming Nodejs uses events heavily and it is also one of the reasons why Nodejs is pretty fast compared to other similar technologies. Event-driven programming is used to synchronize the occurrence of multiple events and to make the program as simple as possible.
All the API of Nodejs is single and stays asynchronous. There is a main loop monitoring things and triggering the appropriate callbacks. Create an instance of EventEmitter.
Nodejs has a built-in module called Events where you can create- fire- and listen for- your own events. Nodejs uses events heavily and it is also one of the reasons why Nodejs is pretty fast compared to other similar technologies. The simplest form of the event-driven nature is the callback style of some of the popular Nodejs functions for example fsreadFile.
While the operating system is doing this work NodeJS can let its one thread continue on doing other work while it waits. Leveraging the JavaScript. Event-driven programming is a programming paradigm in which the flow of the program is determined by events such as user actions mouse clicks key presses sensor outputs or messages from other programsthreads.
It is the one of the reason why Nodejs is pretty fast compared to. To include the built-in Events module use the require method.
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Nodejs Is Single Threaded It Is Event Driven And Single Threaded With Background Workers Scaling Up A Node Application Is Possible By Sp Single Event Driving
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