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HTML5 Hyper Text Markup Language version 5
WEB PROGRAMMING HTML5 Hyper Text Markup Language version 5
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Introduction to HTML5 HTML5 is a markup language that specifies the structure and content of documents that are displayed in web browsers. Creation by typing HTML5 markup text in a text editor (such as Notepad, TextEdit, vi, emacs) and saving it with the .html or .htm filename extension. Computers called web servers storeHTML5 documents. Clients request specific resources such asHTML5 documents from web servers.
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First Example
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Document Type Declaration
Mandatory one Browsers render the page in standards mode, according to the HTML and CSS specifications. Blank Lines Lines 2 & 10 to make our documents easier to read Browser ignores them Comments Lines 3 & 4 To improve readability and describe the content of a document. Browser ignores them. start with <!-- and end with -->.
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html, head and body Elements
HTML5 markup contains text, images, graphics, animations, audios and videos that represents the content of a document and elements that specify a document’s structure and meaning. The html element encloses the head section (represented by the head element) and the body section(represented by the body element). The head section contains information about the HTML5 document, such as the character set (UTF-8, the most popular character-encoding scheme for the web) helps the browser determine how to render the content and the title. Head section also can contain special document-formatting instructions called CSS3 style sheets and client-side programs called scripts for creating dynamic web pages. The body section contains the page’s content, which the browser displays when the user visits the web page.
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Start Tags and End Tags HTML5 documents delimit most elements with a start tag and an end tag. A start tag consists of the element name in angle brackets (for example, <html> ) An end tag consists of the element name preceded by a forward slash (/) in angle brackets (for example, </html>) There are several so-called “void elements” that do not have end tags. Many start tags have attributes that provide additional information about an element, which browsers use to determine how to process the element. Each attribute has a name and a value separated by an equals sign (=).
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Paragraph Element (<p>...</p>)
title Element This is called a nested element, because it’s enclosed in the head element’s start and end tags. The title element describes the web page. Paragraph Element (<p>...</p>) All the text placed between the <p> and </p> tags forms one paragraph. Helps to define the structure of a document. End Tags This document ends with two end tags, which close the body and html elements.
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Headings HTML5 provides six heading elements (h1 through h6) for specifying the relative importance of information. Heading element h1 is considered the most significant one and is typically rendered in a larger font than the other five.4 Each successive heading element (h2, h3, etc.) is typically rendered in a progressively smaller font.
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Linking references (or links to) other resources, such as HTML5 documents and images. Any displayed element can act as a hyperlink. Web browsers typically underline text hyperlinks and color their text blue by default so that users can distinguish hyperlinks from plain text. The strong element, which indicates that its content has high importance. Browsers typically render such text in a bold font. Links are created using the a (anchor) element. Line 16 defines a hyperlink to the URL assigned to attribute href (hypertext reference), which specifies a resource’s location, such as a web page or location within a web page, a file, an address. If the web server cannot locate a requested document, it returns an error indication to the web browser (known as a 404 error), and the browser displays a web page containing an error message.
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Hyperlinking to an E-Mail Address
Anchors can link to addresses using a mailto: URL. When the user clicks this type of anchored link, most browsers launch the user’s default program (for example, Mozilla Thunderbird, Microsoft Outlook or Apple Mail) to enable the user to write an message to the linked address. The form of an anchor is <a href = "mailto: Address">…</a>.
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Images The most popular image formats used by web developers today are PNG (Portable Network Graphics) and JPEG (Joint Photographic Experts Group). an img element to include an image in the document. The image file’s location is specified with the src (source) attribute. This image is located in the same directory as the HTML5 document, so only the image’s file name is required. This is known as a relative path. Optional attributes width and height specify the image’s dimensions. We can scale an image by increasing or decreasing the values of the image width and height attributes. Images are measured in pixels (“picture elements”), which represent dots of color on the screen. Image-editing programs display the dimensions, in pixels, of an image.
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1. alt Attribute 2. Void Elements
Every img element in an HTML5 document must have an alt attribute. If a browser cannot render an image, the browser displays the alt attribute’s value. Figure 2.6 shows the Internet Explorer browser rendering a red X symbol and displaying the alt attribute’s value, signifying that the image (jhtp.png) cannot be found. 2. Void Elements Some HTML5 elements (called void elements) contain only attributes and do not mark up text. terminate void elements (such as the img element) by using the forward slash character (/) inside the closing right angle bracket (>) of the start tag.
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3. Using Images as Hyperlinks
create an image hyperlink by nesting an img element in an anchor element. The img element’s src attribute value specifies that this image (links.jpg) resides in a directory named buttons. Images from other web documents also can be referenced by setting the src attribute to the name and location of the image. Clicking an image hyperlink takes a user to the web page specified by the surrounding anchor element’s href attribute. When the mouse hovers over a link of any kind, the URL that the link points to is displayed in the status bar at the bottom of the browser window.
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Lists The unordered-list element ul creates a list in which each item begins with a bullet symbol (typically a disc). Each entry in an unordered list is an li (list item) element. Most web browsers render each li element on a new line with a bullet symbol indented from the beginning of the line.
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Nested Lists Lists may be nested to represent hierarchical relationships. The ordered-list element ol creates a list in which each item begins with a number. In many browsers, the items in the outermost unordered list are preceded by discs. List items nested inside the unordered list are preceded in many browsers by hollow circular bullets. Subsequent nested unordered list items are often preceded by square bullets. The bullet styles used may vary by browser.
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Tables Tables are frequently used to organize data into rows and columns. Tables are defined with the table element. The border attribute with the value "1" specifies that the browser should place borders around the table and the table’s cells. The caption element specifies a table’s title. Text in this element is typically rendered above the table. A table has three distinct sections—head, body and foot. The head section (or header cell) is defined with a thead element which contains header information such as column names. Each tr element defines an individual table row. The columns in the thead section are defined with th elements. Most browsers center text formatted by th (table header column) elements and display them in bold. Table header elements are nested inside table row elements.
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The body section, or table body, contains the table’s primary data.
The table body is defined in a tbody element. In the table body, each tr element specifies one row. Data cells contain individual pieces of data and are defined with td (table data) elements in each row. The tfoot section is defined with a tfoot (table foot) element. The text placed in the footer commonly includes calculation results and footnotes.
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Using rowspan and colspan with Tables
Table cells are sized to fit the data they contain, but you can control a table’s formatting using CSS3. We can create cells that apply to more than one row or column using the attributes rowspan and colspan. The values assigned to these attributes specify the number of rows or columns occupied by a cell. The br element, which most browsers render as a line break.
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Forms Forms – collecting data from user.
Data that users enter on a web page is normally sent to a web server that provides access to a site’s resources. These resources are located either on the same machine as the web server or on a machine that the web server can access through the Internet. A request contains the name and path of the desired resource and the protocol (method of communication). HTML5 documents are requested and transferred via the Hypertext Transfer Protocol (HTTP).
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This is a simple form that sends data to the web server for processing
This is a simple form that sends data to the web server for processing. The web server typically returns a web page back to the web browser—this page often indicates whether or not the form’s data was processed correctly.
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method Attribute of the form Element
Specifies how the form’s data is sent to the web server. Using method = "post" appends form data to the browser request, which contains the protocol (HTTP) and the requested resource’s URL. This method of passing data to the server is transparent—the user doesn’t see the data after the form is submitted. The other possible value, method = "get", appends the form data directly to the end of the URL of the script, where it’s visible in the browser’s Address field.
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action Attribute of the form Element
specifies the URL of a script on the web server that will be invoked to process the form’s data. input elements that specify data to provide to the script that processes the form (also called the form handler). An input’s type is determined by its type attribute. This form uses a text input, a submit input, a reset input and three hidden inputs.
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text input, submit and reset input Elements
The text input inserts a text field in the form. Users can type data in text fields. The label element provides users with information about the input element’s purpose. The submit input element is a button. When the submit button is pressed, the form’s data is sent to the location specified in the form’s action attribute. The value attribute sets the text displayed on the button. The reset input element allows a user to reset all form elements to their default values.
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New HTML5 Form input Types
input Type color input Type date input Type datetime input Type datetime-local input Type input Type month input Type number input Type range input Type search input Type tel input Type time input Type url input Type week
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1. input Type color enables the user to enter a color.
when you click a color input, browsers will likely display a color picker similar to the Microsoft Windows color dialog shown in Fig. 3.2.
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autofocus Attribute an optional attribute
used in only one input element on a form automatically gives the focus to the input element, allowing the user to begin typing in that element immediately. Figure 3.3 shows autofocus on the color element—the first input element in our form—as rendered in Chrome.
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Validation The new HTML 5 input types are self validating on the client side. The server should still validate all user input. When a user enters data into a form then submits the form, the browser immediately checks the self-validating elements to ensure that the data is correct. to bypass validation, you can add the formnovalidate attribute to input type submit in line 101: <input type = "submit" value = "Submit" formnovalidate />
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2. input Type date enables the user to enter a date in the form yyyy-mm-dd. The start date is the current date. when the user clicks a date input, browsers are likely to display a date control similar to the Microsoft Windows one shown in Fig. 3.6.
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4. input Type datetime-local
enables the user to enter a date (year, month, day), time (hour, minute, second, fraction of a second) and the time zone set to UTC (Coordinated Universal Time or Universal Time, Coordinated). 4. input Type datetime-local enables the user to enter the date and time in a single control. The data is entered as year, month, day, hour, minute, second and fraction of a second.
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5. input Type enables the user to enter an address or a list of addresses separated by commas. HTML5 does not check whether an address entered by the user actually exists— rather it just validates that the address is in the proper format.
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placeholder Attribute
allows you to place temporary text in a text field. Generally, placeholder text is light gray and provides an example of the text and/or text format the user should enter. HTML5 supports placeholder text for only six input types—text, search, url, tel, and password.
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required Attribute forces the user to enter a value before submitting the form. You can add required to any of the input types.
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6. input Type month 7. input Type number
enables the user to enter a year and month in the format yyyy-mm, such as 7. input Type number enables the user to enter a numerical value—mobile browsers typically display a numeric keypad for this input type. The min attribute sets the minimum valid number, in this case "0". The max attribute sets the maximum valid number, which we set to "7". The step attribute determines the increment in which the numbers increase. In this case “1”. If the user attempts to enter an invalid value by typing in the text field, a callout pointing to the number input element will instruct the user to enter a valid value.
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9. input Type search 8. input Type range
appears as a slider control in Chrome, Safari and Opera (Fig. 3.12). You can set the minimum and maximum and specify a value. 9. input Type search provides a search field for entering a query. This input element is functionally equivalent to an input of type text.
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10. input Type tel enables the user to enter a telephone number—mobile browsers typically display a keypad specific to entering phone numbers for this input type. HTML5 does not self validate the tel input type. To ensure that the user enters a phone number in a proper format, we have to add a pattern attribute to determine whether the number is in the format.
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12. input Type url 13. input Type week 11. input Type time
enables the user to enter an hour, minute, seconds and fraction of second time must have two digits representing the hour, followed by a colon (:) and two digits representing the minute. 12. input Type url enables the user to enter a URL. The element is rendered as a text field, and the proper format is HTML5 does not check whether the URL entered is valid; rather it validates that the URL entered is in the proper format. 13. input Type week enables the user to select a year and week number in the format yyyy-Wnn, where nn is 01–53
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input Element autocomplete Attribute
can be used on input types to automatically fill in the user’s information based on previous input—such as name, address or e- mail. input Element datalist Attribute provides input options for a text input element. datalist support varies by browser. If the user types "M" in the text field, the list on months is narrowed to March and May.
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