Master RxJS: Part 2 – What is an observer

This is the second post in the Master RxJS series. The first post is a video tutorial that explains, why RxJS Watch it here: https://www.youtube.com/watch?v=GfuGIh-Bmxw In this post, we will discuss an observer in RxJS. An observer is an object with three call-back functions to subscribe to the notifications from an Observable. Too much technical … Continue reading Master RxJS: Part 2 – What is an observer

How to make the length of an Array read-only in JavaScript

Sometimes, you may come across a requirement that once the array is created, its length should not be changed. In this blog post, let us explore how you can achieve that. Let us say you have an array as shown below, let foo = ['1', '11']; console.log(foo.length); // 2 console.log(foo[1]); //11 As you see, the length of the array is 2, and … Continue reading How to make the length of an Array read-only in JavaScript

Link Constructors prototypes to create Inheritance in JavaScript

In JavaScript, there are multiple ways to create an object. However, among all the most popular is using a function as a constructor.   A function returns a newly created object if it is called using the new, which is also known as Constructor Invocation Pattern. You can create a function constructor like any other … Continue reading Link Constructors prototypes to create Inheritance in JavaScript

How Object.entries work internally in JavaScript

In JavaScript, the Object.entries method returns an array of object’s own enumerable properties. It returns properties as a [key, value] pair, where the key is a string. You can read enumerable properties as an array of key-value pairs using the Object.entries method as shown below, let Product = {     Title: 'Book',     Price: 120,     Author: undefined,     inStock: true } console.log(Object.entries(Product)); Since it returns … Continue reading How Object.entries work internally in JavaScript

Working with objects in a JavaScript Arrow Function

The JavaScript Arrow function is a shorter way of writing a function expression. Let us say you have a function expression as below, var add = function (num1, num2) {     return num1 + num2; } The above function can refactor for a shorter syntax using the arrow function as below, var add = (num1, num2) => num1 + num2;  So, as you see, the arrow function provides a convenient and short syntax … Continue reading Working with objects in a JavaScript Arrow Function

Why use new.target inside a function in JavaScript – Simplified

There are four invocation patterns in JavaScript, which means you can call a function in four possible ways. They are, Function Invocation PatternConstructor Invocation PatternMethod Invocation PatternIndirect Invocation Pattern Essentially, these four-invocation patterns determine the value of ‘this’ object inside a function.  Let us consider the function created below, function add(num1, num2) {     console.log(this); // global object  } let a = add(8, 9);  In the … Continue reading Why use new.target inside a function in JavaScript – Simplified

How to use for…of loop with an Object in JavaScript

In my last post, I discussed Always Use the for…of loop to iterate in JavaScript. After this post, I got a question that, is it possible to use for…of loop with an object? Means, can you use the for…of loop to iterates properties of an object.  Let us try this, let Product = {     Id: 1,     Title: 'Pen',     Price: 1000,     sendDetail: () => { } … Continue reading How to use for…of loop with an Object in JavaScript

Always Use the for…of loop to iterate in JavaScript

In JavaScript to iterate over the values of an array, map, object, etc. use the for…of loop. In a specified order, it iterates over the set of values of an iterable object such that array. It would be best if you use a for…of loop for looping. You must have used the for…in loop to … Continue reading Always Use the for…of loop to iterate in JavaScript

The simplest way to Remove Duplicate Items from a JavaScript Array

You may have often come across a requirement to remove duplicate items from a JavaScript array. There are multiple ways to achieve it. Such that, Using the forEach loop and manually checking for the duplicate valuesUsing the array’s filter method and othersUsing the Set object Let us say; you have an array as below, let … Continue reading The simplest way to Remove Duplicate Items from a JavaScript Array

Using Spread Syntax to Merge Objects in JavaScript

Have you come across a requirement to merge two or more object in another object? Most simply, you can achieve it by using JavaScript Spread syntax (…). Due to its multi functionalities purpose, JavaScript Spread Syntax is one of the most useful operators. You can use it, Rest parameters to a functionTo merge two and … Continue reading Using Spread Syntax to Merge Objects in JavaScript