This is the attribute type you would use to specify URLs or other arbitrary user data. ID indicates the attribute value is a unique identifier within the scope of the document. The definition and use of unparsed general entities is covered in Section These names are given to the processing application as the value of the attribute.
How they are used is determined by the application. In addition to these keyword-based types, you can create an enumerated type by listing the specific values allowed with this attribute. To create an enumerated type, list the allowed values, separated by vertical bars and enclosed in parentheses, as the type of the attribute.
The method attribute accepts one of two values, either get or post ; get is the default value if nothing is specified in the document tag. After you define the name and type of an attribute, you must specify how the XML processor should handle default or required values for the attribute. You do this by supplying one of four values after the attribute type.
The IMPLIED keyword means that the attribute may be used but is not required and that no default value is associated with the attribute. Classes allow authors to define specific kinds of a given element. Unlike with the id attribute, any number of elements can share the same class.
An element may also belong to multiple classes; the class attribute value is a space-separated list of class names. Note that some older browsers do not support multiple classes.
Such browsers typically ignore a class attribute that specifies multiple classes. The class attribute is particularly useful when combined with style sheets. For example, consider the following navigation bar:. This example's use of the class attribute allows style rules to easily be added. The following Cascading Style Sheet suggests a presentation for the preceding example:. The style attribute allows authors to specify style rules inline for a single occurrence of an element.
An example follows:. When the style attribute is used, a default style sheet language must be specified for the document by setting the Content-Style-Type HTTP header to the media type of the style sheet language. The previous example could use the following meta element in the document's head :. In most cases, use of the class or id attributes is a better choice than using style since id and class can be selectively applied to different media and since they provide a separation of content and presentation that often simplifies maintenance.
The title attribute provides a title for an element and is commonly implemented as a "tooltip" on visual browsers, though many browsers lack support for title. The attribute is most useful with a , link , img , and object elements, where it provides a title for the linked or embedded resource.
Some examples follow:. Listed below are several types of markup elements used in HTML. Structural markup describes the purpose of text.
Structural markup does not denote any specific rendering, but most Web browsers have standardized default styles for element formatting. Presentational markup describes the appearance of the text, regardless of its function. Most presentational markup elements have become deprecated under the HTML 4. Hypertext markup links parts of the document to other documents. Let's now look at attributes. Attributes are written within the start tag of an element, after the element's name. The abbreviation element, abbr , can be used to demonstrate these various attributes:.
In most browsers, pointing the cursor at the abbreviation should display the title text "Hypertext Markup Language. Empty elements consist of only a single tag, with any attributes. Attributes define desired behavior or indicate additional element properties. In keeping with the principle of Separation of Concerns , the function of HTML is primarily to add structural and semantic information to the raw text of a document. In other words: HTML just defines what kind of text or typographic elements you have inside a document , e.
Web browsers have a built-in method to render each of these elements, e. The advantage of this strategy is that you may use the same style for lots of pages, e. This also means, that you can easly change the look of all your page that use the same styelsheet s. Finally, you may associate several stylesheets to a page and that offers an extra set functionalities. For example, you can load a large "official" stylesheet that will cover most of your needs and then you can fine-tune styling by adding your own on top.
You also may create different stylesheets for different media, in particular: one for normal viewers, one for visually impaired viewers and one for printing that filters out elements like navigation menus that you won't need on pager. Markup of an HTML page is divided into two big parts: the head contains information that the user will not see inside the browser window and the body contains the contents to be displayed.
We can express this with a simple formula:. You may have a look at the real page by clicking here. However, this HTML code is not totally complete. There exist different variants for HTML. Let's now look at a larger gallery of complete examples before we start introducing X HTML elements and attributes.
HTML 4. Correct HTML files should include the following document type declaration information starting on line 1. Before we add more explanation we suggest that you either use HTML 4. The rationale for including this information is that display will be better when the browser knows what kind of X HTML you intended to use.
As a web designer you must cope with several issues. Here are some of these issues that you should look at once you'll get past learning basic HTML:. In the head element we may defines various important information about an HTML page. Its contents are not displayed. Specifies links to other documents, such as previous and next links, or alternate versions. A common use is to link to external stylesheets, using the form:. Can be used to specify additional metadata about a document, such as its author, publication date, expiration date, page description, keywords, or other information not provided through the other header elements and attributes.
For instance, the content attribute defines both the mime type and the character set. Define a document title. User agents e. Typically, the title is displayed on the window decoration. For obvious reasons, only text is allowed within a title element. It then goes on for dozens of lines. Many modern web pages though use reasonably short headers.
Inside the body tag, a variety of high level elements may used in any order. The following pseudo-formal rule includes the most important ones:. Read the rule like this: Inside the body tag you may include any of these tags as much as you like and in any order.
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