JavaScript full course

This course will be updated as we move on. It serves as an all-in guide for people new to JavaScript. I am open to directions on what the guide should cover. Thanks for reading😊

Introduction to JavaScript

Javascript

javascript, often shortened as JS, is a programming language
that is one of the core technologies of the World Wide Web (WWW),
alongside HTML and CSS. It lets us add interactivity to pages, eg.
When you click a button on different websites. All that is built using JavaScript.

Javascript is an interpreted language (or just-in-time compiled), and as you know,
it is a scripting language for the web, alongside many non-browser environments (Node.js,
Apache CouchDB and Adobe Acrobat)

Just-in-time compiled

Just-in-time or JIT compilation is a compilation of codes during the execution of a program at runtime rather than before execution.

Notes: Javascript can be executed from the browser within the terminal using Node.js.
Node.js is a Javascript runtime for running Javascript programs outside a browser environment.

Javascript as an object-oriented programming

Thus, a variable is a container for a value.

variable declaration

It is a way to let the compiler be aware of the existence of a variable within the Javascript codebase.

To declare a variable, you will need a keyword(var, let, const), variable name, and optionally initializing it to a value.

There are three ways to let the compiler be aware of the presence of a variable. These ways involve the use of keywords:

• var: A statement declares function scoped or globally scoped variables, optionally initializing each to a value.

var index = "1"; 
// This is a variable with a String data value.

• let: a statement that declares a reassignable block-scoped variable, optionally initializing each to a value.

let index = 2;
//This is a variable with an integer data value

• const: a block-scoped variable that cannot change value by reassignment or redeclaration. Compared to the other keywords, const must be initialized to a value.

const options = true;
//This is a variable with a boolean data value

Breakdown of a variable

Keyword (var, let, const) + variable name (letters) + assignment operator (=) + value(datatypes)

Hoisting

Hoisting is a Javascript mechanism where variable and function declarations are moved to the top of their scope before code execution.

Scopes

It refers to the visibility of a variable or how it can be used after it is declared. The scope of a variable depends on the keyword that was used to declare it.

There are three types of scopes in ES6 and they are Global scopes, Function scopes and block Scope.

• Global scope: Variables declared outside any function or curly braces{} have a Global Scope, and can be accessed from anywhere within the same JavaScript code. var, let and const have access to this scope.

• Function Scope: variables within a function can only be used within the same function. Outside that function, they are undefined. var, let and const all provide this Scope.

• Block Scope: A block is any part of Javascript code bounded by {}. Variables declared withi a block can not be accessed outside that block. This scope is only provided by the let and const keyword

Data types

Strings

Strings are characters written inside a single or double quotes. They are similarly a sequence of text (alphabetical, numeric and alphanumeric).

String Methods

Length : The length property returns the length of a string

const string1 = "Ebube";
console.log(string1.length);

at : gets the exact character per the position(index).

const string1 = "Ebube";
console.log(string1.at(0));

charAt : gets the exact character per the position(index).

const string1 = "Ebube";
console.log(string1.charAt(0));

charCodeAt: it returns the code of the character at a specified index in a string

const string1 = "Ebube";
console.log(string1.charCodeAt(0));

property access: you can access string characters through their index. Like how arrays work

const string1 = "Ebube";
console.log(string1[0]);