Fall 2016 CSULA Saloni Chacha CS 1220 Web Programming Fall 2016 CSULA Saloni Chacha
HTML5 Introduction HTML is a markup language for describing web documents (web pages). HTML stands for Hyper Text Markup Language A markup language is a set of markup tags HTML documents are described by HTML tags Each HTML tag describes different document content
Sample HTML Code <!DOCTYPE html> <html> <head> <title>Page Title</title> </head> <body> <h1>My First Heading</h1> <p>My first paragraph.</p> </body> </html>
Example Explained The <!DOCTYPE html> declaration defines this document to be HTML5 The text between <html> and </html> describes an HTML document The text between <head> and </head> provides information about the document The text between <title> and </title> provides a title for the document The text between <body> and </body> describes the visible page content The text between <h1> and </h1> describes a heading The text between <p> and </p> describes a paragraph
HTML Tags HTML tags are keywords (tag names) surrounded by angle brackets: <tagname>content goes here...</tagname> HTML tags normally come in pairs like <p> and </p> The first tag in a pair is the start tag, the second tag is the end tag The end tag is written like the start tag, but with a forward slash inserted before the tag name
The <!DOCTYPE> Declaration The <!DOCTYPE> declaration represents the document type, and helps the browser to display a web page correctly. It must only appear once, at the top of the page (before any HTML tags). There are different document types. To display a web page correctly, the browser must know both type and version. The doctype declaration is not case sensitive. All cases are acceptable: <!DOCTYPE html> <!doctype HTML>
HTML Attributes All HTML elements can have attributes Attributes provide additional information about an element Attributes are always specified in the start tag Attributes usually come in name/value pairs like: name="value“ The lang Attribute The language of the document can be declared in the <html> tag. The language is declared with the lang attribute. Declaring a language is important for accessibility applications (screen readers) and search engines: <html lang="en-US">
The href Attribute HTML links are defined with the <a> tag. The link address is specified in the href attribute: <a href="http://www.w3schools.com">This is a link</a>
Size Attributes HTML images are defined with the <img> tag. The filename of the source (src), and the size of the image (width and height) are all provided as attributes: <img src="w3schools.jpg" width="104" height="142">
The alt Attribute The alt attribute specifies an alternative text to be used, when an image cannot be displayed. The value of the attribute can be read by screen readers. This way, someone "listening" to the webpage, e.g. a blind person, can "hear" the element. <img src="w3schools.jpg" alt="W3Schools.com" width="104" hei ght="142">
Size Attributes HTML images are defined with the <img> tag. The filename of the source (src), and the size of the image (width and height) are all provided as attributes: <img src="w3schools.jpg" width="104" height="142">
Why Use CSS? CSS is used to define styles for your web pages, including the design, layout and variations in display for different devices and screen sizes. HTML was NEVER intended to contain tags for formatting a web page! HTML was created to describe the content of a web page, like: <h1>This is a heading</h1> <p>This is a paragraph.</p> When tags like <font>, and color attributes were added to the HTML 3.2 specification, it started a nightmare for web developers. Development of large websites, where fonts and color information were added to every single page, became a long and expensive process. To solve this problem, the World Wide Web Consortium (W3C) created CSS. CSS removed the style formatting from the HTML page!
CSS Syntax A CSS rule-set consists of a selector and a declaration block:
Syntax The selector points to the HTML element you want to style. The declaration block contains one or more declarations separated by semicolons. Each declaration includes a CSS property name and a value, separated by a colon. A CSS declaration always ends with a semicolon, and declaration blocks are surrounded by curly braces. In the following example all <p> elements will be center-aligned, with a red text color:
Syntax p { color: red; text-align: center; }
CSS Selectors and Element Selector CSS selectors are used to "find" (or select) HTML elements based on their element name, id, class, attribute, and more The element selector selects elements based on the element name. You can select all <p> elements on a page like this (in this case, all <p> elements will be center-aligned, with a red text color): p { text-align: center; color: red; }
The id Selector The id selector uses the id attribute of an HTML element to select a specific element. The id of an element should be unique within a page, so the id selector is used to select one unique element! To select an element with a specific id, write a hash (#) character, followed by the id of the element. The style rule below will be applied to the HTML element with id="para1":
The id Selector #para1 { text-align: center; color: red; }
The class Selector The class selector selects elements with a specific class attribute. To select elements with a specific class, write a period (.) character, followed by the name of the class. In the example below, all HTML elements with class="center" will be red and center-aligned: .center { text-align: center; color: red; }