NOVICE

Client-server

HTTP

HyperText Transfer Protocol

Is an application protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web.

What is HTTP?

HTTP is a "language" spoken between clients and servers
Internet Data
An HTTP client makes HTTP requests
An HTTP server accepts HTTP requests, and sends the client an HTTP response

HTTP Methods

GET - I want a resource
POST - I want to send you data
PUT - I want to change a resource
DELETE - I want to delete a resource
HEAD - I just want the response headers
OPTIONS - What methods can I use?

A client uses one of the methods to send HTTP Requests to the server

HTTP

HTTP status code

1xx Informational
2xx Success
- 200 OK
3xx Redirection
4xx Client Error
- 400 Bad Request
- 401 Unauthorized
- 403 Forbidden
- 404 Not Found
5xx Server Error
- 500 Internal Server Error
- 504 Gateway Timeout

HTTP Request URI

Uniform Resource Identifier

URI is how a server identifies a resource to be delivered to the client

Examples

/index.html
/map/21.3088569,-157.8084575

URL

Uniform Resource Locator

A URL is a URI that also specifies how to get that resource (what protocol to use)

Examples

https://www.google.com
http://www.devleague.com/apply

https://www.google.com

http://www.devleague.com:80/apply

http://162.243.46.54:80/parting-thoughts-from-a-student/

Protocol

Host address

port

path

HTTP Request

the default port to make HTTP requests is 80

The HTTP Request Response cycle starts with the HTTP Request

An HTTP Request is a client connecting to a host (server that is listening for incoming messages) and sending a Request Message

HTTP Response

An HTTP Response is the server replying to the client's original HTTP Request with a message and the requested resource

HTML

HyperText Markup Language

In the late 1980s, Tim Berners-Lee was working as a physicist at CERN (the European Organization for Nuclear Research). He devised a way for scientists to share documents over the internet.

What is HTML?

Markup language
Defines content for the browser to display
Separates "content" and "presentation"
Pre-defined set of elements (tags)

W3C

World Wide Web Consortium

The main international standards organization for the World Wide Web (abbreviated WWW or W3)

Specification Maturation

Working Draft (WD)
Candidate Recommendation (CR)
Proposed Recommendation (PR)
W3C Recommendation (REC)

HTML

Versions

HTML 0.9
RFC 1866 — HTML 2.0
HTML 3.2 — 14 jan. 1997 year;
HTML 4.0 — 18 dec. 1997 year;
HTML 4.01 — 24 dec. 1999 year;
HTML5 — 28 oct. 2014 year
HTML 5.1 — from 17 dec. 2012 year.

Doctype HTML 4

This DTD contains all HTML elements and attributes, but does NOT INCLUDE presentational or deprecated elements (like font). Framesets are not allowed.

HTML 4.01 Strict

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

HTML 4.01 Transitional

This DTD contains all HTML elements and attributes, INCLUDING presentational and deprecated elements (like font). Framesets are not allowed.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

HTML 4.01 Frameset

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">

This DTD is equal to HTML 4.01 Transitional, but allows the use of frameset content.

Doctype XHTML 1.0

Strict

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

This DTD contains all HTML elements and attributes, but does NOT INCLUDE presentational or deprecated elements (like font). Framesets are not allowed. The markup must also be written as well-formed XML.

Transitional

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

This DTD contains all HTML elements and attributes, INCLUDING presentational and deprecated elements (like font). Framesets are not allowed. The markup must also be written as well-formed XML.

Frameset

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">

This DTD is equal to XHTML 1.0 Transitional, but allows the use of frameset content.

Doctype

This DTD is equal to XHTML 1.0 Strict, but allows you to add modules (for example to provide ruby support for East-Asian languages).

HTML 5

XHTML 1.1

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">

<!DOCTYPE html>

Simple HTML Page

<!DOCTYPE html>
<html>

  <head>
    <title>My first page</title>
  </head>
  
  <body>
    <p>Hello <b>world!</b></p>
  </body>

</html>

HTML structure

Text containing markup tags
Markup tags tell the browser how to display the page

Basic HTML

All HTML documents must start with the type declaration of HTML: <!doctype HTML>
The HTML document itself begins with <html> and ends with </html>
The visible part of the HTML document is between <body> & </body>
The information about the page like title of the page, scripts, styles and meta data is between <head> & </head>

<!doctype html>
<html>
<head>
    <title>My First Webpage</title>
</head>
<body>
    <h1>Heading</h1>
    <p>This is a paragraph</p>        
</body>
</html>

html head

According to the HTML standard, only a few tags are legal inside the head section

<head>

Defines information about the document

<title>

<link>

<meta>

<!DOCTYPE>

Defines the document type. This tag goes before the <html> start tag.

Defines a resource reference

Defines meta information

Defines the document title

Attributes

The start tag may contain additional information. Such information is called an attribute

ATTRIBUTES USUALLY CONSIST OF 2 PARTS:

An attribute name
An attribute value

<input required="required">
<p class="example">Tag with attributes</p>
<span id="identificator">Tag with id</span>
<div title="This is a DIV.">A sentence.</div>

Attributes are placed inside an element's first tag
They are placed after the tag name
You're assigning (=) a value to an attribute

Comment

HTML has a mechanism for embedding comments that are not displayed when the page is rendered in a browser .

This is useful for explaining a section of markup, or leaving notes for other people who might work on the page, or for leaving reminders for yourself.

HTML comments are enclosed in symbols as follows:

<!doctype html>
<html>
<head>
    <title>My First Webpage</title>
</head>
<body>
    <!-- The page content -->
    <h1>Heading</h1>
    <p>This is a paragraph</p>        
</body>
</html>

ELEMENTS

HTML consists of a set of elements
Elements define the semantic meaning of their content
Include everything between two matching element tags , including the tags themselves

Some elements have very precise meaning, as in "this is an image", or "this is a heading". Others are less specific, such as "this is a section on the page" or "this is part of the text."

<html>
  <body>
    <p>You are in your beginning stage of</p>
    <p>HTML</p>
  </body>
</html>

This structure is often thought of as a tree with branches (in this case, the <body> and <p> elements) growing from the trunk (<html>). This hierarchical structure is called the DOM : the Document Object Model

NESTING

Nesting is the act of placing an HTML element inside another HTML element. You can nest tags infinitely -- as your project requires it.
In this example, <p> tags were inside our <body> tag. Our <body> tag was also inside our <html> tag. Accordingly, this will be how the resulting web page is structured.

<html>
  <body>
    <p>You are in your beginning stage of</p>
    <p>HTML</p>
  </body>
</html>

HTML is forgiving

Unknown element tags are ignored
Unknown attributes are ignored
Unknown values are ignored
Browser tries to close tags itself if they are not closed

Sandbox

CSS

Cascading Style Sheets

Is a style sheet language used for describing the look and formatting of a document written in a markup language.

CSS is designed primarily to enable the separation of document content from document presentation, including elements such as the layout, colors, and fonts

Simple CSS

body {
    background: red;
    color: blue;
    font-size: 12px;
}

Unfortunately, the CSS language is considerably different from the HTML language.

However, like HTML, it is very easy to understand and write.

Syntax

CSS has a very straightforward syntax.

Your CSS is divided into rules. Each rule has two parts: a selector and one or more declarations (each of which has a property and a value).

Selector

The selector does exactly what it sounds like: it selects certain parts of your HTML document. There're a few ways for you to do this. The simplest is to simply u se a tag name

This'll select all the <h1> tags in your document:

h1 { 
    *put your declarations here*
}

Declaration

Once you've selected a set of elements, use declarations to change their visual properties.
Declarations come after a selector, and are enclosed in curly-brackets {like these}
Don't forget that semi-colon! It'll lead to big problems later on!

Format

Each declaration has the format:

property: value;

Ruleset

Each (valid) declaration block is preceded by a selector which is a condition selecting some elements of the page.
The pair selector-declarations block is called a ruleset, or often simply a rule.

Font

Another common task is changing the appearance of your text. Once again, CSS has plenty of ways to do this

To change text size, use "font-size":

To change font, use the "font-family" property:

To change alignment, use "text-align":

h1 {
    font-family: "Times New Roman";
}

h1 {
    font-size: 22pt;
}

h1 {
    text-align: center;
}

Color

ANOTHER COMMON TASK IS CHANGING THE Color OF a TEXT or background

To change text color, use "color":

h1 {
    color: blue;
}

To change background color, use "background-color":

body {
    background-color: grey;
}

COMBINING PROPERTIES

You can add any number of properties to a declaration

body {
    background-color: green;
    text-align: center;
    font-family: "Arial";
}

p {
    color: yellow;
    font-size: 14px;
}

Apply css to HTML

THere are 3 ways to apply CSS to HTML page:

Inline
Internal
External

Inline style

Added directly to element in thestyle attribute
Only stylesthe element on current page
Not reusable
Avoid whenever it is possible

<!DOCTYPE html>
<html>
  <head>
    <title>Inline</title>
  </head>
  <body>
    <p style="color: red;">Supporting paragraph. Very informative.</p>
  </body>
</html>

Internal stylesheets

Added to <head> between <style> tags
Only styles elements on current page
Avoid whenever it is possible

<!DOCTYPE html>
<html>
  <head>
    <title>Internal</title>
    <style>
      h1 {
          font-size:50px;
          text-align: center;
        }
    </style>
  </head>
  <body>
    <h1>This is my huge headline</h1>
    <p>Supporting paragraph. Very informative.</p>
  </body>
</html>

External stylesheets

Completely separate file, linked in <head>
The file has extension ".css"
Reusable styles contained in 1 document
Best practice - use this one!

<!DOCTYPE html>
<html>
  <head>
    <title>External</title>
    <link rel="stylesheet" href="mystyles.css">
  </head>
  <body>
    <p>This is my snazzy red paragraph!</p>
  </body>
</html>

HTML FIle

mystyles.css

body {
  width: 1000px;
  margin: auto;
}

p {
  color: red;
  text-align: center;
}

Page example

CSS

HTML

body {
    background-color: green;
    text-align: center;
    font-family: "Arial";
}

p {
    color: yellow;
    font-size: 14px;
}

<!DOCTYPE html>
<html>

  <head>
    <title>My first page</title>
    <link rel="stylesheet" href="styles.css">
  </head>
  
  <body>
    <p>Hello world!</p>
  </body>

</html>

Sandbox

JS

Javascript

Is a high level, dynamic, untyped, and interpreted programming language. It has been standardized in the ECMAScript language specification. Alongside HTML and CSS, it is one of the three essential technologies of World Wide Web

What is JavaScript

JavaScript is a Scripting Language
A scripting language is a lightweight programming language.
JavaScript is programming code that can be inserted into HTML pages.
JavaScript inserted into HTML pages, can be executed by all modern web browsers.

History

1995 - 1997

Created by Brendan Eich for Netscape Navigator in only ten days!
Mocha ⇒ LiveScript ⇒ JavaScript ⇒ ECMAScript
Influenced by:
- C/Java ⇒ Syntax
- Scheme ⇒ Functional Programming
- Self ⇒ Prototype inheritance
Adopted by Microsoft with the name JS for IE 3.0 ...
- First browser wars!
Standarized by ECMA International.

History

1998 - 2002

W3C: DOM Level 1 and DOM Level 2
Microsoft created XMLHttpRequest
Microsoft won the war with IE 6

History

2003 - 2008

Mozilla Firefox was born
AJAX acronym is coined
Google becomes more than just a search engine: GMail, Maps
First JavaScript libraries: Prototype, Scriptaculous, etc
JQuery: now DOM is easy

History

2009 - NOW

Google Chrome was born
ECMAScript 5 was approved
It began the era of mobile applications (SPA, mobile first)
HTML5 & CSS3
MV* frameworks move to the client: Angular, Backbone, etc.
Server side JavaScript: Node.js
JavaScript grows up

Why JavaScript?

The name suggests that it should be similar to Java, but it is a different beast
The language was created too quickly and has errors that many programmers do not care to avoid
Still exists the idea that serious programming is done on the server and many programmers do not bother to learn JavaScript seriously

It supports multiple paradigms: imperative or functional
It is very flexible and expressive
There have been significant improvements in performance
The language is improving with the latest versions
Whenever there are better books, tools, libraries, etc

JavaScript is a misunderstood language

But in JavaScript there are great ideas too

Why JavaScript?

It is easy to learn
It is easy to write, execute, test and debug
It is the most widely used language
On the client has beaten all its rivals:
- VBScript
- ActionScript (Flash)
- Applets (Java)
On the server is becoming a major player (Node.js)
Web applications can be built using only JavaScript:
- Front-end development
- Back-end development
- Server services (Web servers, message queuing services, authentication services, etc)
- JSON for client-server communication
- Even database structures (BSON) and query language (MongoDB, CouchDB)
Isomorphic JavaScript: The Future of Web Apps?

WHAT CAN I DO WITH JAVASCRIPT?

Respond to the users actions (click, hover over etc.)
Change HTML&CSS properties of elements on the page
Sophisticated animations
Dynamically get new data from the server without reloading the entire page (AJAX)

Hello World!

Basics

JavaScript is case sensitive
Spaces do not matter
Statements end with semi-columns (;)
No strict data types

Comments

Commentaries are not for the computer but for the humans. It helps them to understand the code

Block (multiline)

code goes here  /*  comment goes here,  
                    and here
                */

Single-line comments

code goes here //comment goes here

/*
    My first program:
    Hello World!
*/
var a = "Hello World!"; //Declare new variable with initial value
alert(a); //Show message window with the content of the "a" variable

Example

Variable Declaration

Variables contain values and use the equal sign to specify their value
Variables are created by declaration using the var command with or without an initial value state
No need to specify a type

Declare variable without initial value:

var a;
var oneMore;
var anotherVar;
var awesomeVariable;

Declare variable with initial value:

var b = 10;
var name = "Leonardo";
var price = 10.4;

Set value to variable

To set new value to a variable you are to use the equal sign "="
New data overwrites the previous one
No strict data type. It means that you can set any value with any type to a variable

//Declaration of a new variable with initial value below
var greeting = "Say hello to the new world of programming!" 

var a;
a = 10; //You can set the value after the variable declaration

var name = "Raphael";
name = "Donatello"; //It will overwrites the content of the "name" variable

var age = 10;
age = "Teenager"; //No type checking

Arithmetics

Operator	Description	Example
+	Addition	var x = 10 + 2;
-	Subtraction	var x = 5 - 3;
*	Multiplication	var x = 2 * 2;
/	Division	var x = 20 / 5;
%	Modulus	var x = 10 % 4;
++	Increment	x++;
--	Decrement	x--;

var a = 10; 
a++; 
var b = a * 2;
b = b - 1;
b--;
var c = b / 2;
c = c - a;
var x = b & 8;

//a == 10;
//a == 11;
//b == 22; a == 11;
//b == 21;
//b == 20;
//c == 10;
//c == -1;
//x = 4;

EMBEDDING JAVASCRIPT IN HTML

inner script code

<!DOCTYPE html>
<html>

  <head>
    <title>My first page</title>
  </head>
  
  <body>
    <h1>Example</h1>

    <script language="javascript" type="text/javascript">
        var a = "Hello World!";
        alert(a); 
    </script>
  </body>

</html>

EMBEDDING JAVASCRIPT IN HTML

External script code

index.html

<!DOCTYPE html>
<html>

  <head>
    <title>My first page</title>
  </head>
  
  <body>
    <h1>Example</h1>

    <script language="javascript" type="text/javascript" src="script.js">
    </script>
  </body>

</html>

var a = "Hello World!";
alert(a);

script.js

EMBEDDING JAVASCRIPT IN HTML

Inline script code

<!DOCTYPE html>
<html>

  <head>
    <title>My first page</title>
  </head>
  
  <body>
    <h1>Example</h1>
    <p onclick="alert('Hello World!')">Say hello</p>
  </body>

</html>

Sandbox

HTML Editor

Write HTML Using Notepad

HTML can be edited by using professional HTML editors like:

WebStorm
Sublime Text
Atom
Brackets
...

However, for learning HTML I recommend a text editor like Notepad (PC) or TextEdit (Mac).
Using a simple text editor is a good way to learn HTML.

Step 1: Open Notepad

To open Notepad in Windows 7 or earlier:
- Click Start (bottom left on your screen). Click All Programs. Click Accessories. Click Notepad.
To open Notepad in Windows 8 or later:
- Open the Start Screen (the window symbol at the bottom left on your screen). Type Notepad.

Step 2: Write Some HTML

<!DOCTYPE html>
<html>

  <head>
    <title>My first page</title>
  </head>
  
  <body>
    <p>Hello <b>world!</b></p>
  </body>

</html>

Step 3: Save the HTML Page

Select File > Save as in the Notepad menu.
Name the file "index.html" or any other name ending with html or htm.
UTF-8 is the preferred encoding for HTML files.

View HTML Page in Your Browser

Open the saved HTML file in your favorite browser

Page load order

The browser sends a request to the server
The server starts sending to the browser the html-code of the page. The specifics of the data on the Internet is that the code for the browser receives the page not once, but piecemeal
To save time, the browser starts processing of html-code of the page, without waiting for the end of the document
Once the browser encounters an external resource, it sends to the server a request for the resource. At the same time, in most cases, if the resource is javascript file then the browser stops loading the page and starts executing javascript-code of this file
Once the browser receives and processes html-code of the page (the handler has reached the closing tag html), the browser is event DOMContentLoaded, also known as the DOM Ready.
Once the last external resource is loaded, the browser triggers the event window.onload. Page is fully loaded.

Page load order

Conclusion

HTML is for data structure
CSS is about how this data looks
JS is about this data manipulation and user interaction

What we've learnt

What is client-side architecture
What is HTTP Protocol
What is HTML, its history, versions, doctypes
Basic HTML page structure
Simple HTML tags and their nesting
What is CSS, its purpose
CSS selectors, properties
Basic CSS Rules
How to apply CSS to HTML
What is JavaScript, its history
Why we should learn JS
Variables, Arithmetic Operators
Variables assignment
Hot to add JS to HTML
Page loading order

Class work

Create empty HTML document
Fill it with basic HTML markup
Add first level header and two paragraphs with any text

Create empty CSS file
Add it to the HTML document
Add rule to make the header to be red
Change the font size of the paragraph

Create empty JavaScript file
Declare three variables with your name, last name and age
Alert them one by one
On the header click show alert with any text

Check yourself

Home work

https://events.yandex.ru/lib/talks/532/ - Об истории браузеров

https://events.yandex.ru/lib/talks/1329/ - Механизм работы браузера

https://events.yandex.ru/lib/talks/542/ - Языки программирования (первые 30 минут)

NOVICE

Client-server

HTTP

HyperText Transfer Protocol

What is HTTP?

HTTP Methods

A client uses one of the methods to send HTTP Requests to the server

HTTP

HTTP status code

HTTP Request URI

Uniform Resource Identifier

URL

Uniform Resource Locator

HTTP Request

the default port to make HTTP requests is 80

HTTP Response

HTML

HyperText Markup Language

W3C

World Wide Web Consortium

HTML

Versions

Doctype HTML 4

Doctype XHTML 1.0

Doctype

Simple HTML Page

HTML structure

Basic HTML

html head

According to the HTML standard, only a few tags are legal inside the head section

tAGS

Attributes

The start tag may contain additional information. Such information is called an attribute

Comment

ELEMENTS

NESTING

HTML is forgiving

Sandbox

CSS

Cascading Style Sheets

Simple CSS

Syntax

Selector

Declaration

Ruleset

Font

Another common task is changing the appearance of your text. Once again, CSS has plenty of ways to do this

Color

ANOTHER COMMON TASK IS CHANGING THE Color OF a TEXT or background

COMBINING PROPERTIES

You can add any number of properties to a declaration

Apply css to HTML

THere are 3 ways to apply CSS to HTML page:

Inline style

Internal stylesheets

External stylesheets

Page example

Sandbox

JS

Javascript

What is JavaScript

History

1995 - 1997

History

1998 - 2002

History

2003 - 2008

History

2009 - NOW

Why JavaScript?

Why JavaScript?

WHAT CAN I DO WITH JAVASCRIPT?

Hello World!

Basics

Comments

Commentaries are not for the computer but for the humans. It helps them to understand the code

Variable Declaration

Set value to variable

Arithmetics

EMBEDDING JAVASCRIPT IN HTML