General Assembly

Web development: breaking it down

By Chen Hui Jing / @hj_chen

General Assembly

Internet basics

What is the internet?

The entire network of networks that connect all the world's devices to each other

How does the internet work?

Internet ≠ World wide web

	Internet	World wide web
Estimated year of origin	1969	1993
Name of first version	ARPAnet	NSFnet
Comprises	Network of devices, copper wires, fibre-optic cables and wireless networks	Files, folders & documents stored in various computers
Governed by	Internet Protocol (IP)	Hypertext Transfer Protocol (HTTP)
Dependency	None, everything else depends on it	The internet
Nature	Hardware	Software

Source: Diffen

Protocols

A protocol is an agreed set of rules and standards that allow devices to communicate with each other.

Internet Protocol (IP)	To route information to the proper address
Hypertext Transfer Protocol (HTTP)	For the transmission of web pages over the internet
Transmission Control Protocol (TCP)	To create packets, reassemble them, make sure none were lost in transmission
Simple Mail Transfer Protocol (SMTP)	For computers to send email
Post Office Protocol (POP)	For computers to receive email
File Transfer Protocol (FTP)	For copying files over a network from one computer to another

General Assembly

About web development

What is web development?

The process of building websites

How to get started?

Your computer

This image is pure CSS.

Modified from this brilliant codepen by Will Paige

A clear mind

Code is numbers, letters and symbols

Regardless of what programming language you use, all code can be read in any text editor.

Javascript

close: function () {
  this.ul.setAttribute("hidden", "");
  this.index = -1;

  $.fire(this.input, "awesomplete-close");
},

Code credit: Lea Verou

#include "8cc.h"
static int count_leading_ones(char c) {
  for (int i = 7; i >= 0; i--)
      if ((c & (1 << i)) == 0)
          return 7 - i;
  return 8;
}

Code credit: Rui Ueyama

Assembly

ctable	 segment para public 'DATA
  db	9 dup(' ')
  db	9,10,' ',12,13
  db	13 dup(' ')
  db	27
  db	4 dup(' ')
  db	' !"#$%&',39,'()*+,-./0123456789:;<=>?@'
  db	'ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`'

Code credit: Happy codings

General Assembly

Programming for the web

Front-end

Client-side

Back-end

Server-side

Feeling overwhelmed?

HTML and CSS are the foundation of the web

Basic technology stack

General Assembly

Hypertext Mark-up Language (HTML)

Structures the document and tells browsers what a certain element's function is
Content is "marked-up" using tags

Tags usually (but not always) come in pairs,

<p>This is an example of a paragraph element</p>

The opening tag, closing tag and everything in between is a HTML element

History of HTML

Invented by Tim Berners-Lee in 1989 as a means for easy linking of references in research papers using hypertext
Created the Hypertext Transfer Protocol (HTTP) for retrieving text from other documents via hypertext links
Specifications were introduced as a guide for standardisation among browser vendors

Structure of HTML document

<!DOCTYPE html>
<html>
  <head>
    <title>Example page</title>
  </head>
  <body>
    <h1>Hello world</h1>
  </body>
</html>

Document type element

<!DOCTYPE html>

Appears just above the <html> tag
Tells the browser to render the HTML in standards mode
Let's validation software know which version of HTML to validate against
Advised to use the HTML5 doctype

`<html>` element

<html lang="en">
// HTML code for web page
</html>

Represents the root of an HTML document
Encouraged to specify a language attribute
Language attribute aids speech synthesis (screen readers), translation tools and other language-related functionality

`<head>` element

<head>
  <meta charset="utf-8">
  <title>Your site title</title>
  <meta name="description" content="A short description of your website">
  <meta name="author" content="Your name">
  
  <link rel="stylesheet" href="css/styles.css?v=1.0">
</head>

Contains instructions for the browser and meta data for the website
Title and description are what shows up on search engine results
Stylesheets are also declared here

`<body>` element

<body>
  <header>
    <img src="img/logo.png" alt="Site logo">
    <nav>
      <ul>
        <li><a href="#">Home</a></li>
        <li><a href="#">About</a></li>
        <li><a href="#">Contact</a></li>
      </ul>
    </nav>
  </header>
  <main>
    <h1>Page header</h1>
    <p>Some content in a paragraph. Brownie tiramisu toffee sweet roll sesame snaps halvah. Fruitcake donut pie ice cream jujubes danish dragée. Bear claw jelly dessert lemon drops bonbon donut. Sugar plum sugar plum candy canes ice cream powder tootsie roll sweet. Sugar plum biscuit macaroon fruitcake cookie cupcake jelly-o cupcake. </p>
  <main>
</body>

Represents the main content of the document
Should only be one <body> element on a web page

Formatting your web page

<address>
<article>
<footer>
<header>
<h1>
<h2>
<h3>
<h4>
<h5>
<h6>
<hgroup>
<nav>
<section>
<dd>
<div>
<dl>
<dt>
<figcaption>
<figure>
<hr>
<li>
<main>
<ol>
<p>
<pre>
<ul>
<caption>
<col>
<colgroup>
<table>
<tbody>
<td>
<tfoot>
<th>
<thead>
<tr>
<button>
<datalist>
<fieldset>
<form>
<input>
<keygen>
<label>
<legend>
<meter>
<optgroup>
<option>
<output>
<progress>
<select>
<details>
<dialog>
<menu>
<menuitem>
<summary>
<abbr>
<b>
<bdi>
<bdo>
<br>
<cite>
<code>
<data>
<dfn>
<em>
<i>
<kbd>
<mark>
<q>
<rp>
<rt>
<rtc>
<ruby>
<s>
<samp>
<small>
<span>
<strong>
<sub>
<sup>
<time>
<u>
<var>
<wbr>
<area>
<audio>
<map>
<track>
<video>
<embed>
<object>
<param>
<source>
<canvas>
<noscript>
<script>
<del>
<ins>

Semantics and accessibility

To make the web easier to use and access, and available to everyone
Encompasses all disabilities, including visual, auditory, physical, speech, cognitive and neurological disabilities
Benefits people without disabilities as well
Accessible websites benefit from search engine optimisation (SEO)

Basic accessibility checklist (1/2)

Page title: To adequately and briefly describe the content of the page
Image text alternatives: To make visual information accessible
Headings: To provide meaningful hierarchy for facilitation of navigation
Contrast ratio: To have sufficient luminance contrast ratio, for people with different requirements
Resize text: To ensure visibility and usability as text size increases

Basic accessibility checklist (2/2)

Keyboard access & visual focus: To provide full functionality through a keyboard, and visible focus with logical order
Forms, labels & errors: To have proper labels, keyboard access, clear instructions, and effective error handling
Multimedia alternatives: To have alternative formats for audio and visual impaired

Visit Web Accessibility Initiative (WAI) to understand more about this important aspect of the web

General Assembly

Cascading Style Sheets (CSS)

Tells the browser how to display a certain element
Follows the general ruleset:

Select the HTML element to be styled
Specify the properties of the element to be styled
Give the values we want each property to have

Structure of a CSS rule

selector {
  property1: value;
  property2: value;
  property3: value;
}

The selector identifies which HTML elements the rule will be applied to
The curly braces contain the property-value pairs, separated with semi-colons
The properties define the style of the selected element
The values are dependent on the property, and indicate the value of the properties to be set

Types of CSS selectors

Element: matches all the elements of that name on the page
```
p {}
```
Class: matches all the elements with the specified class attribute, e.g. <div class="example">
```
.example {}
```
ID: matches the element with the specified id attribute, e.g. <div id="example">
```
#example {}
```

CSS Specificity

0-∞

Inline styles

0-∞

IDs

0-∞

Classes, attributes and pseudo-classes

0-∞

Elements and pseudo-elements

ul {
  // CSS properties
}

0, 0, 0, 1

.class-1 .class-2 p {
  // CSS properties
}

0, 0, 2, 1

#id-1 .class-3 div {
  // CSS properties
}

0, 1, 1, 1

General Assembly

Javascript

A cross-platform, object-oriented scripting language
Can run directly in the browser, does not need to be compiled first
Allows greater control of web page behaviour
Is a full-fledged programming language, with operators, control structures and statements

Brief history of Javascript

Invented in 10 days by Brendan Eich of Netscape
Was taken to the European Computer Manufacturers Association (ECMA) for standardisation in 1996
Currently on the 6th edition, known as ECMAScript 2015, or ES6

Client-side vs Server-side

Client-side Javascript

Provides a means of controlling the browser and its Document Object Model
Examples are form validation, load more buttons, image galleries and so on

Server-side Javascript

Usually refers to node.js
Provides a customised response based on user (client) requests
For example, displaying your profile information after you logged in

What is an API?

Stands for Application Programming Interface
A means for your web page to access data from another source
Usually a URL, that when accessed, returns data in a standardised format (often, JSON)

Example weather API

// 20160211134054
// http://api.openweathermap.org/data/2.5/weather?id=1880251&appid=44db6a862fba0b067b1930da0d769e98

{
  "coord": {
    "lon": 103.8,
    "lat": 1.37
  },
  "weather": [
    {
      "id": 803,
      "main": "Clouds",
      "description": "broken clouds",
      "icon": "04d"
    }
  ],
  "base": "stations",
  "main": {
    "temp": 302.15,
    "pressure": 1010,
    "humidity": 74,
    "temp_min": 302.15,
    "temp_max": 302.15
  },
  "visibility": 10000,
  "wind": {
    "speed": 5.1,
    "deg": 30
  },
  "clouds": {
    "all": 75
  },
  "dt": 1455166800,
  "sys": {
    "type": 1,
    "id": 8145,
    "message": 0.0091,
    "country": "SG",
    "sunrise": 1455146219,
    "sunset": 1455189666
  },
  "id": 1880251,
  "name": "Republic of Singapore",
  "cod": 200
}

Web APIs

Give the browser and server the ability to perform many tasks
DOM is actually an API that allows access and modification of the web page
Device APIs let web developers access hardware features
Communication APIs let devices, applications and web pages talk to each other, e.g. web notifications, push etc.

General Assembly

Resources

To find out more...

Dash (online course)
Codeacademy (online course)
Bento (online resources)
Mozilla Developer Network (MDN) (website)
HTML & CSS: Design and Build Web Sites by Jon Duckett (book)
Eloquent Javascript by Marijn Haverbeke (book)

Sign up for GA courses

General Assembly

THE END

https://www.chenhuijing.com

@hj_chen

@huijing

Web development: breaking it down

Internet basics

What is the internet?

How does the internet work?

Internet ≠ World wide web

Protocols

About web development

What is web development?

How to get started?

Code is numbers, letters and symbols

Programming for the web

Front-end

Back-end

Feeling overwhelmed?

HTML and CSS are the foundation of the web

Basic technology stack

Hypertext Mark-up Language (HTML)

Hypertext Mark-up Language (HTML)

History of HTML

Structure of HTML document

Document type element

<html> element

<head> element

<body> element

Formatting your web page

Semantics and accessibility

Basic accessibility checklist (1/2)

Basic accessibility checklist (2/2)

Cascading Style Sheets (CSS)

Cascading Style Sheets (CSS)

Structure of a CSS rule

Types of CSS selectors

CSS Specificity

Javascript

Javascript

Brief history of Javascript

Client-side vs Server-side

What is an API?

Example weather API

Web APIs

Resources

To find out more...

Sign up for GA courses

THE END

`<html>` element

`<head>` element

`<body>` element