•Its one of the most powerful and highly in-demand programming language.

•Choice of Google, Microsoft, Linux Foundation, 10Gen and Mozilla

JavaScript – Weird and Amazing

Introduction:

Latest Trends in Programming Languages

• According to data provided by one of the largest social networks for programmers and software development platform "Github", Javascript is leading programming language.
• According to a survey conducted by "stackoverflow", Javascript is market leader in most of the domains in industry.

JavaScript – Weird and Amazing

Similarity b/w Java and JavaScript

JavaScript – Weird and Amazing

JavaScript  ===  Java

if and only if

 Car === Carpet.

Some of you may be interested in 

•It was written by a guy named Brandon Eiac within just 7 or 10 days in 1995

•For browsers? Not Intentionally but eventually

•First Browser to adopt JavaScript was Netscape (Mozilla).

•Influenced greatly by Scheme programming language.

•Different JavaScript.

JavaScript – Weird and Amazing

History of JavaScript:

• Almost everywhere.
• Competing Java, Python and Ruby like languages.
• Not just web, but every platform.
• JQuery, Angular, Node, Express, Kraken, Ionic and Electron are just JavaScript.

JavaScript – Weird and Amazing

Where is it now? (Why should  you learn it?)

JavaScript – Weird and Amazing

SAAD ABBASI               S. M. TAHA

But why us?

• Learning Javascript and its frameworks including NodeJS, Angular2, JQuery.
• Follow me and my projects github.com/SMTaha.
• Member of Karachi.js.
• Certificate of completion in HTML, CSS and JavaScript from The Hong Kong University of Science and Technology

• Full Stack MEAN & MEA2N Developer.
• Follow me and my projects github.com/isaadabbasi.
• Started off with Java, but …
• Member of Karachi.js.
• Data Visualization using socket.IO & D3.

• Basic to Advanced syntax.
• Deep dive into core logic.
• Complex problem solving.
• Interview questions.
• Word Alerts.
• Weird and Amazing parts.

JavaScript – Weird and Amazing

What are we going to cover

At the end of the course you will be able to understand codes like

JavaScript – Weird and Amazing

function timebomb(){
    var _arr = [];
    setTimeout(function(){
        for (var i=0; i<3; i++){
            _arr.push((function(j){
                return function(){
                    console.log( j );
                }
            }(i)))
        }
    }, 1000);
    return _arr == [] ? null : _arr;
}
console.log(timebomb());

function mess(){
    var array = [];
    for(var i=0; i<5; i++){
        array.push(
            (function(j){
                return function(){            
                    console.log(j);
                }
            }(i))
        )
    }
    return array;
}
for (i in mess())
    console.log( mess()[i]() );

JavaScript – Weird and Amazing

 SO,

LETS GET STARTED

JavaScript – Weird and Amazing

Understanding the Nature of JS

Synchronous 

&

Single Theraded

• One at a time

JavaScript – Weird and Amazing

Synchronous 

• JavaScript is Single Threaded.
• Only one command at a time.

JavaScript – Weird and Amazing

Single Threaded

SYNTAX PARSERS,
EXECUTION CONTEXT AND

LEXICAL ENVIORNMENTS

JavaScript – Weird and Amazing

SYNTAX PARSER:

A PROGRAM THAT READS YOUR CODE AND DETERMINES WHAT IT DOES AND IF ITS GRAMMAR IS VALID

Your code isn't magic. Someone else wrote a program to translate it for computer.

JavaScript – Weird and Amazing

LEXICAL ENVIRONMENT:

WHERE SOMETHING SITS PHYSICALLY  IN THE CODE YOU WRITE

'Lexical' means 'having to do with words or grammar'. A lexical environment exist in programming language in which where you write something is important.

JavaScript – Weird and Amazing

EXECUTION CONTEXT:

A WRAPPER TO HELP MANAGE THE CODE THAT IS RUNNING

There are lots of lexical environments. Which one is currently running is managed via execution contexts. It can contain things beyond what you've written in your code.

JavaScript – Weird and Amazing

Its important!

NAME/VALUE PAIRS AND OBJECTS

JavaScript – Weird and Amazing

NAME/VALUE PAIR:

A NAME WHICH MAPS TO A UNIQUE VALUE

The name may be defined more than once, but only can have one value in any given context.

That value may be more name/value pairs.

JavaScript – Weird and Amazing

OBJECT:

A COLLECTION OF NAME VALUE PAIRS

The simplest definition when talking about Javascript.

JavaScript – Weird and Amazing

THE GLOBAL ENVIRONMENT AND  THE GLOBAL OBJECT

JavaScript – Weird and Amazing

GLOBAL

• "Not Inside a Function

JavaScript – Weird and Amazing

FUNCTION INVOCATION

AND

THE EXECUTION STACK

JavaScript – Weird and Amazing

INVOCATION:

RUNNING A FUNCTION

In Javascript, by using parenthesis ()

JavaScript – Weird and Amazing

EXECUTION STACK

FUNCTION, CONTEXT

AND

VARIABLE ENVIRONMENTS

JavaScript – Weird and Amazing

VARIABLE ENVIRONMENT:

WHERE THE VARIABLES LIVE

And how they relate to each other in memory

JavaScript – Weird and Amazing