Complete theory Javascript from zero to expert

 Javascript is a high-level object-oriented multi-paradigm programming language

what do we actually use for 

HTML 

CSS 

Javascript hide paragraph 

Interactive effects allow Dynamic effects and web applications in the browser

React Angular Vajue Based on javascript Front-end 

Node js Back-end applications

Objects and primitives 

VALUE 

OBJECT 

let me ={

name:'Jonas'

};

Or PRIMITIVE 

let firstName = 'Jonas';

let age = 30;

There are 7 primitive data types

1 NUMBER floating point numbers used for decimals and integers let age = 23;

2 STRING sequence of characters used for text let firstName = 'Jonas';

3 BOOLEAN Logical type that can only be true or false used for taking decisions let fullAge = true;

4 UNDEFINED: Value has taken by a variable that is not yet defined ('empty value) let children;

5 NULL also means an empty value

6 symbol (ES2015) Value

Three forms to call variables in js 

Let: could change in the future 

Const: can't change in the future 

ALWAYS USE CONST 

var job = ' programmer';

job = 'teacher';

Var can change in the future 

OPERATORS

There are many types of operators

STRINGS

Template literals 

const valeryNew = `I'm ${firstName}, ${ birthYear}`;

 

Strings 

`${const}`

Regular string 

console.log(`just a regular string ...`);

String multiple lines 

console.log(`string

multiple

lines`);

Taking decisions 

Decision if else 

if (){

} else {

}if else{

}

Decision Booleans 

&& AND 

CONDITIONALS OPERATORS 

An operator always produces a value

ternary operators 

    

JAVASCRIPT RELEASES: ES5, ES6+ AND ESNEXT

A brief history of Javascript 

1995 creates the very first version of js in just 10 days

1996 Changed to LiveScript and then to JavaScript, in order to attract Java developers, Js is very different from java.

Microsoft launches IE copying Javascript from Netscape and called it Jscrit

In 1997 with a need to standardize the language ECMA releases ECMAScript 1 the first official standard for Javascript (ECMAScript is the standard, Javascript is the language in practice);

2009 ES5 (ECMAScript 5) is released with lots of great new features;

2015 ES6/ES2015 (ECMAScript 2015) was released: THE BIGGEST UPDATE TO THE LANGUAGE EVER.

ECMAScript changes to an annual release cycle in order to ship fewer features per update

BACKWARDS COMPATIBILITY: Don't break the web 

1997 compatible 2020

Old features are never removed 

Not really new versions just incremental updates

websites keep working forever

HOW TO USE MODERN JAVASCRIPT TODAY

During development: Simply use the latest Chrome 

During production: Use babel to transpile and polyfill your code converting back to ES5 to ensure the browser is compatible with all users).

ES5 Fully supported in all browsers( down to IE 9 from 2011)

Ready to be used today

ES6/ES2015 ES6+ well supported in all modern browsers 

ES2020                    No support in older browsers

                                 Can use most features in production with transpiring and poly filling.

MODERN JAVASCRIPT FROM THE BEGINNING 

Learn modern Javascript from the beginning

Functions Js

Can hold one or more code lines 

Function calling a function