INTRODUCTION

GENERAL

CLIENT-SERVER

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

WHAT IS HTTP?

  • 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 METHODS

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 REQUESTS

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

URI

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

URL

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

HTTP RESPONSE

HyperText Markup Language

HTML

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

WHAT IS HTML?

HISTORY

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.

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)

W3C

  • HTML 0.9
  • RFC 1966 — 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.

HTML VERSIONS

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: HTML 4

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: XHTML 1.0

HTML 5

<!DOCTYPE html>

DOCTYPE: HTML 5

<!DOCTYPE html>
<html>

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

</html>
  • Text containing markup tags
  • Markup tags tell the browser how to display the page

HTML STRUCTURE

  • 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>

BASIC HTML

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

HTML HEAD

HTML attaches special meaning to anything that starts with the less-than sign ("<") and ends with the greater-than sign (">"). Such markup is called a  tag.

  1. Make sure to close the tag, as some tags are closed by default, whereas others might produce unexpected errors if you forget the end tag. 
  2. Proper nesting is one rule that must be obeyed in order to write valid  code.

Tags gotchas

Correct

Wrong

<p>This <b>is</p> incorrect</b>
<p>This <b>is</b> correct</p>

TAGS

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

ATTRIBUTES USUALLY CONSIST OF 2 PARTS:

  1. An attribute  name
  2. 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

ATTRIBUTES

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>

COMMENTS

  • 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

ELEMENTS

  • 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>

NESTING

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

HTML IS FORGIVING

SANDBOX

Cascading Style Sheets

CSS

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

WHAT IS 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. 

SIMPLE CSS

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).

CSS selector

SYNTAX

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*
}

SELECTOR

  • 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;

DECLARATION

  • 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.

RULESET

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;
}

FONT

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;
}

COLOR

There are 3 ways to apply CSS to HTML page:

  • Inline
  • Internal
  • External

WAYS TO APPLY CSS

  • 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>

INLINE STYLES

  • 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>

INTERNAL 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;
}

EXTERNAL STYLESHEETS

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>

PAGE EXAMPLE

SANDBOX

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.  

WHAT IS JAVASCRIPT?

  • 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: 1995 -1997

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

HISTORY: 1998 - 2002

  • 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: 2003 - 2008

  • 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

HISTORY: 2009 - NOW

  • 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?

WHY 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)

WHAT CAN I DO WITH JS?

HELLO WORLD!

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

BASICS

 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

COMMENTS

  • 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;

VARIABLE DECLARATION

  • 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

SETTING VALUE TO A VARIABLE

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;

ARITHMETICS

EMBEDDING JAVASCRIPT IN HTML

  • Inner script
  • External script
  • Inline script
<!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>

INNER SCRIPT

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

EXTERNAL SCRIPT

<!DOCTYPE html>
<html>

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

</html>

INLINE SCRIPT

SANDBOX

PAGE LOADING

  1. The browser sends a request to the server.
  2. 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.
  3. To save time, the browser starts processing of html-code of the page, without waiting for the end of the document
  4. 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.
  5. Once the browser receives and processes html-code of the page, the browser is event DOMContentLoaded, also known as the DOM Ready.
  6. Once the last external resource is loaded, the browser triggers the event window.onload. Page is fully loaded.

PAGE LOAD ORDER

PAGE LOAD ORDER

TOOLS

IDE

WebStorm

Sublime Text

Atom

Brackets

TOOLS FOR LEARNING

Notepad

Notepad++

VERSION CONTROL

WHAT IS VERSION CONTROL?

Version control is a system that records changes to a file or set of files over time so that you can recall specific versions later.

GIT

Git is a free and open source version control system designed to handle everything from small to very large projects with speed and efficiency.

GIT TREE

A branch represents an independent line of development. You can think of them as a way to request a brand new working directory, staging area, and project history.

A commit is a snapshot of your current changes to the project history.

GIT REPOSITORIES

A local repository is a repository on your local machine. It keeps your local working copy.

A remote repository contains versions of your project that are hosted on the Internet or network somewhere.

GIT CLONE

To clone a remote repository into a newly created directory use clone command: 

git clone

GIT ADD

The "index" holds a snapshot of the content of the working tree. It is used for tracking your files.

It is a multipurpose command – you use it to begin tracking new files, to stage files, and to do other things like marking merge-conflicted files as resolved.

git add

To start tracking files use add command:

GIT PULL & PUSH

To upload changes from a remote branch you should use pull command:

 To apply changes to a remote branch you should use push command:

git push
git pull

GIT WORKFLOW

  • HTML is for data structure
  • CSS is about how this data looks
  • JS is about this data manipulation and user interaction
  • Version control systems are used by developers for collective development 

CONCLUSION

  • 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
  • Version Control

WHAT WE'VE LEARNED

PRACTICE

  • 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 1: OPEN NOTEPAD

<!DOCTYPE html>
<html>

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

</html>

STEP 2: WRITE SOME HTML

  • 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.

STEP 3: SAVE THE HTML PAGE

Open the saved HTML file in your favorite browser

STEP 4: OPEN PAGE IN BROWSER

CHECK YOURSELF

  • 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

TASK

  • Upload source code to github

 Об истории браузеров

https://events.yandex.ru/lib/talks/532/

Механизм работы браузера

https://events.yandex.ru/lib/talks/1329/

Языки программирования (первые 30 минут)

https://events.yandex.ru/lib/talks/542/

Watch videos:

HOMEWORK

Useful links:

GIT documentation

https://git-scm.com/doc

GIT tutorial

https://githowto.com/ru

INTRODUCTION

By sinelshchikovigor

Source: Dima Pikulin

INTRODUCTION

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