NodeJs/JavaScript

What is JavaScript It is a scripting language that is the core of websites, along with HTML and ...

Script tag You can insert JavaScript program into HTML document using the <script> tags. You ca...

Variables A named storage for storing data. There are couple way of creating a variable var ke...

String Conversion You can call the String() function to explicit convert a value to a string St...

Math Operators +, addition -, subtraction *, multiplication /, division %, remainder **, ex...

Ternary Operator let accessAllowed; if (age > 18) { accessedAllowed = true; } else { ...

While and for loop They are the same as in Python, C, and Java while (condition) { // Repeat ...

Function Declaration To declare a function follow the syntax: function function_name(parameter1...

Objects In JavaScript objects are used to store key to value pair collection of data. You can th...

Reachability In JavaScript garbage collection is implemented through something called reachabili...

Constructor function Function that is meant to be a constructor are named with capital letter fi...

Optional chaining There is this problem that if the object that you are accessing might or might...

Symbols In JavaScript there is two primitive types that can be used as object property key St...

Array Two ways of creating empty array let arr = new Array(); let arr = []; Create an array w...

Iterables A generalization of arrays, it allows us to make any object iterable in the context of...

Map Very similar to an object, however, with object the only key that is allowed is a String. Ma...

Destructuring assignment A special syntax to let us unpack either array or object into different...

JSON file When you want to transport say a complicated object or an array of object to another c...

Rest parameters and spread syntax How do we make a function take in an arbitrary number of argum...

Virtual property In addition to the normal property that we have for objects, we can also set up...

Prototype inheritance Every object have a special hidden property [[Prototype]] it is either nul...

Class basic syntax Besides using a constructor function there is a more advance object oriented ...

Syntax try { // Code } catch (err) { // Error handling } finally { // Excuted always,...

Time before promise, callbacks There are entities in JavaScript that let you schedule asynchrono...

Promise.all This API will allow us to take in an iterable, an array of promises and return a new...

async keyword async keyword is placed before a function like so: async function f() { return ...

Two different standards In the browser JavaScript ecosystem, JavaScript modules depends on impor...