The equality operator in javascript is used to compare if two values are equal. The comparison is made by == and === operators in javascript. The main difference between the == and === operator in javascript is that the == operator does the type conversion of the operands before comparison, whereas the === operator compares the values as well as the data types of the operands. The == and != operators in javascript …
What are express.json() and express.urlencoded()
What is Middleware? It is those methods/functions/operations that are called BETWEEN processing the Request and sending the Response in your application method. When talking about express.json() and express.urlencoded() think specifically about POST requests (i.e. the .post request object) and PUT Requests (i.e. the .put request object) You DO NOT NEED express.json() and express.urlencoded() for GET Requests or DELETE Requests. You NEED express.json() and express.urlencoded() for POST and …
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map() and forEach() in Javascript
The main difference between map and forEach is that the map method returns a new array by applying the callback function on each element of an array, while the forEach method doesn’t return anything.
How to Install Node.js and npm on Windows
Go to Node.js website and download Node.js. Choose the option to install Node.js and npm. When the install finished, check the result in command line:
Some notes on CRUD application – Node.js, Express.js & MongoDB
CRUD – READ In Express, we handle a GET request with the get method: app.get(endpoint, callback) endpoint is the requested endpoint. It’s the value that comes after your domain name. Here are some examples: When you visit localhost:3000, you’re actually visiting localhost:3000/. In this case, browsers requested for /. You’re reading this article on https://zellwk.com/blog/crud-express-mongodb/. …
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Building a functional chat app based on Node.js (2)
Web Sockets Web Sockets are a much more responsive technology, since they keep a connection directly open at all times for each client. This allows either the client or server to directly notify each other when changes occur on their side. In contrast to the request / response model, the server does not wait for …
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Building a functional chat app based on Node.js (1)
Introduction We’ll use our new NodeJS knowledge to build a realistic web server that handles the backend of a messaging app for realtime chatting. We will also create a minimal front end so we can see the service working. These skills will be very applicable to those of you who are creating a web app …
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What is call-back function
What is call back function: Simply put: A callback is a function that is to be executed after another function has finished executing — hence the name ‘call back’. More complexly put: In JavaScript, functions are objects. Because of this, functions can take functions as arguments, and can be returned by other functions. Functions that …
What does “let that = this” mean in Javascript/Typescript?
For example, let person = { name:"bill", speak:function(){ console.log("hi i am "+this.name) } } Functions has something called a context. A context is the object the function is being called on. if you were to do person.speak(), it will be called on the object that was defined. The variable person is the context. So when …
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What is AJAX
What is AJAX AJAX is not a programming language. AJAX is a technique for accessing web servers from a web page. AJAX stands for Asynchronous JavaScript And XML. Here is an example of AJAX: How AJAX works