JavaScript Basics Introduction

 

Adding interactivity To websites

Is it a dynamic weakly typed programming language that is compiled at runtime it can be executed as a part of a webpage in a browser or directly.

user visits & interacts with server request HTML response Client Browser.

The user clicks a button to submit a form 

Js makes this more reactive.

• Hosted language Runs in different 
• Most prominent Run code in a browser

Javascript Engine Your code Build-into the Browser 

Parse code 

Compile machine Code

Execute Machine Code

On a single thread 

Dynamic  

Not pre-compiled instead parsed and compile on the fly (eg on the browser)

Code evaluated and executed at runtime

Code can change at the runtime

Weakly Typed

Data types are assumed (eg assigned variables )automatically

You don't define that some variable has to hold a certain value (eg a number)

Data types are not set in stone but can change 

Javascript on a Host environment 

Browser-side

Javascript was invented to create more dynamic websites by executing the browser 

Js can manipulate the HTML code CSS background Https requests & much more 

js can't access the local filesystem, interact with the operating system, etc

Other (eg server site)

Google's Javascript Engine 

Node,js backends service 

Node,js can access the local filesystem 

Split into three modules

Core basics 

Getting started

Advance Concepts

Setting Up a Development Environment 

IDE/Visual studio code Core Extensions & configuration

Google Chrome

 One of three programming languages for web dev

A programming language that can be executed by browsers. The only programming language browsers can execute 

Update displayed data behind-the-scenes weather data, stocks data, chat messages 

Display or use a timer 

Validate user input and show error message + attach error styles to elements 

Display & manage complex overlays 

Re-order, hide /show or remove elements on the screen 

keep parts of websites working, even if the internet connection lost 

What & why? you can solve problems 

Syntax

Start with variables & values

Array & Object

Functions 

Working with the DOM 

Control structures 

HTML define structure and semantics 

CSS Style the elements and page content 

JavaScript Change the page dynamically (without loading a different HTML file )

Core Javacript syntax 

Operators 

+

-  

* Multiplication

/   Divide

%  divide

** Exponentiation