Hyperlink does not work in html. Hyperlink - what is it, how to make a link and insert it into HTML code (href, target blank and other attributes of the a tag). Link-button using CSS styles

<а href="http://www.mysite.com/doc2.htm/anch3">

That is, we combine the use of the full URL of the document and at the same time point to a certain fragment of it, marked as "anch3".

Rice. 1.16. Browser window showing the result of displaying the file in Listing 1.16

It should be noted that if the text pointed to by the hyperlink is already displayed in the viewport, as happened in our last example, then no change will occur. All you have to do is resize the browser viewport vertically to hide the last line of content that the hyperlink points to, and the result of its action can be visually demonstrated.

Naturally, all names of such bookmark markers, which are defined using the value of the name parameter, must be unique. Be aware, however, that HTML does not distinguish between uppercase and lowercase characters. Therefore, if two bookmarks are defined in our HTML document, which will subsequently be referenced by hyperlinks that differ only in the case of characters, then for the HTML analyzer built into the browser, these identifiers will be considered the same, and it will not process any of them.

However, we already know that it is possible to identify any element of an HTML document using the id parameter, which can be used as part of any tag. At the same time, hyperlinks pointing to document fragments can use these parameters as well, i.e., to set a bookmark marker to a tag, it is not necessary to use the tag<а>with the name parameter, you just need to use the id parameter.

The values ​​for the name parameter and the id parameter are unique identifiers for the elements in the HTML document. Therefore, no value for the name parameter should match any value for the id parameter.

But which option should you choose for your Web pages, which option should you use? Be aware here that while the id parameter can serve several purposes, such as identifying a bookmark marker, creating unique identifiers for executable DHTML scripts and styling, some legacy browsers may not accept these identifiers for targeting hyperlinks.

Together with the tag<а>the title parameter can be used to help identify the hyperlink to the remote user. The value of this parameter is a text string that will be displayed as a small hint when the user hovers the mouse cursor over the desired hyperlink. An ad for such a hyperlink looks like the following:

<а href="www.site.com" title="Very nice site">

Using the hreflang parameter, we can specify the language in which the text content of the Internet resource to which this hyperlink points is written. The parameter value is one of the standard language conventions that we discussed earlier in this chapter.
But specifying the language in which the textual content of a Web page is written is not enough. It is also necessary to indicate the encoding used. And here we can be helped by the already familiar charset parameter, the value of which is the standard designation of the encoding used to display the text content of the Internet resource pointed to by the desired hyperlink.

Using the gel parameter, we can indicate the purpose of the document that the hyperlink points to, that is, the value of this parameter clearly indicates the relationship between the original document and the document we are linking to. Using this parameter has no effect on how the hyperlink is displayed or how the resource is retrieved, but it can be useful. If Web pages are intended not only for viewing with a browser, but also for processing by some specialized applications. Such, for example, as advanced search engines, which are able to correctly recognize and handle such relationships between documents, indicated by hyperlinks.

The rel parameter uses one of the predefined keywords that we will now look at.

• Alternate. The value indicates that the document is an alternate representation of the original document. If the lang parameter is used in the hyperlink with a value that is different from the language of the original document, then such a hyperlink is usually considered a link to a copy of the original document in another language.
• Stylesheet. Indicates that the document referenced by the hyperlink is a style sheet. The mechanism for applying style sheets is described in detail in the second chapter.
• Start. It is used to designate the initial, starting document of a certain set of documents. For a website, this would obviously be the home page.
• Next. The value is used if the starting document and the document pointed to by the hyperlink are in some linear ordered sequence of documents, and the latter is next in sequence with respect to the original Web page.
• Prev. The value is used in the same way as the previous one, but now indicates that the document in the chain is not the next, but the previous one, relative to the starting document.
• index. Used in hyperlinks that point to a document that is the indexed content of the original Web page.
• Glossary. The value indicates that the document contains a glossary of terms used in the original document.
• copyright. Used when the document referenced by the hyperlink contains a copyright notice for the content of the original document.
• chapter. Used in hyperlinks pointing to documents that are separate chapters in a set of documents.
• section. Hyperlink with this parameter value rel indicates a document that is a section in a common set of documents that form a single whole of content.
• subsection. The meaning is a continuation of the concept indicated by the previous meaning we have considered. It means that the document is already subsection.
• Appendix. The value indicates that the document pointed to by the hyperlink is an attachment to the original document.
• Help. Used for links to documents that provide additional reference information in relation to the content of the original document.
• Bookmark. Used for links to HTML documents containing links to some highlighted key fragments of the source document.

When using these values, it should be borne in mind that in this case HTML parsers will be case-sensitive, so you must completely adhere to the spelling shown in our list.

In fact, in HTML there is an opportunity to create your own values ​​for the attribute we are considering, but since to use this parameter to the full, it is necessary to use specialized means of describing these new values ​​and software aimed at recognizing these types of links. Since we are interested in browsers, we don't need to create new types of links.

This technology is actually a palliative, which is designed to provide at least part of the possibilities provided by the new language for describing documents on the Internet - XML ​​(extensible Markup Language), which is predicted to be the successor and "killer" of HTML. But there are no widespread XML browsers yet. applications that process XML documents. And for quite a long time this technology will not become generally accepted, which means that HTML technology still has every right to exist and will be used as the basis for Web pages for a long time to come.

But back to looking at the attributes of the tag<а>... The rev attribute is the opposite of the rel attribute. If the rel attribute specifies the type of document that the hyperlink points to, then the rev attribute specifies the type of the original document that contains the hyperlink. The same set of keywords that was used for the rel attribute is used as the values ​​for this attribute.

Using the target parameter, we specify in which frame the document that the hyperlink points to should be displayed. The point is that usually one document is displayed in one browser viewport. But in HTML it is possible to divide the viewport into several areas, called frames, each of which will display its own HTML document. We will consider the technology of using frames in one of the following sections of this chapter, but for now, we just note that the target parameter allows you to explicitly specify in which frame the Web page should be displayed. Setting up a hyperlink using this parameter will look something like this:

<а href="http://www.mysite.com/docl.html" target="_top">

Such a hyperlink will cause the browser to load the Web page whose URL is specified as the value of the href parameter into the top frame, whose name is specified in the target parameter. The last parameter uses the keywords defined in the HTML specification. We'll cover them in the section on frames.

Some input organs and hyperlinks allow you to move the input focus among themselves using the tabulation key, that is, one press of this key activates the next input organ included in the general sequence. And the order of movement between the controls included in the general sequence is set using the tabindex parameter. As the value of this parameter, an ordinary positive integer is used, and the larger this number is at any data entry body or hyperlink, the later it will come to it when the input focus is moved. Naturally, no pair of Web page design elements should have the same value, otherwise the browser will simply not include them in the sequence of elements with a focus movement.

However, in addition to accessing by successive tab key presses, we can use the access key parameter, the value of which is a character. When the user presses the key that is responsible for entering this character, the Input focus is automatically transferred to the desired hyperlink, in the declaration of which the access key parameter is embedded, and the user can activate it without using the mouse, just by pressing the key ... Let's look at a small example:

<а href="http://www.mysite.com/docl.html" tabindex="2" accesskey="U">

The carrier of a hyperlink can be not only text, but also a graphic image. To do this, you need to place a tag announcing the insertion of graphics into the content of a Web page between the tags<а>and... But the fact is that we can "hang" not one, but several hyperlinks on a graphic image, that is, several active areas are highlighted within the image, clicking on each of them activates the corresponding hyperlink. A similar technology is called segmented graphics.

To create such graphic images associated with multiple hyperlinks, specialized tags are used. First, the active areas of the drawing, also called segments, are declared. All of them make up a map of the active segments of the picture, which is assigned a certain name. And then this map name is associated with the image itself, declared using the tag . Let's consider a typical example.

Listing 1.17

! DOCTYPE HTML PUBLIC "- // W3C // DTD HTML 4.01 // EN"
"http://www.w3.org/TR/htm!4/strict.dtd">




<р>This is plain text.

In this example, you can see that when declaring a picture, in the tag we insert the usemap parameter, the value of which is the name of the map of the active image segments associated with hyperlinks. A hash symbol is inserted before the name of the active segment map used. The description of this card is placed between the tags ... In this case, the opening tag

The map consists of a description of the segments. Each segment is described with one tag<агеа>... We can apply hotspots in three different shapes: rectangles, circles, and polygons. The shape is specified using the required shape parameter. As the value of this parameter, we can use one of the three preset values.

• Meaning rect used to create rectangular hotspots.
• Meaning circle used to create a circular segment.
• Meaning poly allows you to create active segments in the form of convex polygons.

After we have set the type of form, it is necessary to accurately determine their size and location on our graphic image. For this, the coords parameter is used, as the value of which is written a list of coordinates that define the active segment. In Listing 1.17, we can see that the coordinates in the general list are separated by a regular comma. The coordinates are counted from the upper left corner of the picture, which has coordinates (0; 0).

For rectangular segments, specify the coordinates of the upper-left and lower-right corners. And for polygons, the coordinates of all points are sequentially listed, in the order of their connection by lines. Naturally, the first and last pair of coordinates must match, otherwise the polygon will be open and the active segment will not be processed.

Into the tag<аrеа>the href parameter is also included, the value of which is the URL of the resource pointed to by the hyperlink of this segment.
But this parameter, surprisingly, is optional. In the case where a segment is being created but should not be linked to a hyperlink, the nohref parameter should be used, which is irrelevant.
But a required parameter for the tag<аrеа>everything is just like that. This is the alt parameter, which is a text string that is an alternative representation of the picture. As we know, this line is displayed as a hint when the user hovers over the object. In our case, such an object is an active segment embedded in a graphic image.

Also in the tag<агеа>Like normal hyperlink tags, the tabindex and access key parameters are used to activate the hyperlink without using the mouse, using only the keyboard. We examined the structure of the values ​​of these parameters a little earlier. As a sidetrack, it should be noted that any proper webmaster should definitely use these parameters, since only their use can guarantee the activation of hyperlinks without the help of a mouse.

So, we figured out the use of segmented graphics technology. But we have not learned everything about links. The HTML spec defines a tag , which does not create a hyperlink that we are used to, but some connection between the displayed document and some additional file. Tags: can only be placed in the head section of an HTML document, between tags and As an example of the use of the tag we are considering you can give the following piece of code:

Listing 1.18

"http://www.w3.org/TR/html4/strict.dtd">

With this snippet, we indicate that this Web page contains the second chapter of some extensive document, and using tags link to web pages containing the table of contents and the previous and next chapters. The type of document that the link points to is determined using the familiar rel parameter. A normal browser, of course, will not be able to process and display such links in any way. They were introduced into HTML to create documents that would be processed with the help of some specialized applications that allow creating workflow systems based on this format. But the built-in meager capabilities of HTML for creating full-fledged workflow systems were clearly not enough, and when the XML standard was developed, the developers happily changed their favorite.

So it turns out that in regular Web pages the tag absolutely useless? Not really. Only with this tag can we connect Web pages to external style sheets, the most powerful way to control how a document is displayed in a browser. But we will learn about style sheets a little later, in the second chapter. There we will also consider an example of using the tag ... For now, we just have to list the parameters of this tag. All of these parameters apply to tags as well.<а>with the same possible values, so we will not consider each parameter in detail, but simply list them briefly:

• charset- indicates the encoding of the document to which the link points;
• href- the URL of the document to which the link points is used as the value;
• hreflang- the value is the code designation of the language in which the linked document is written;
• type- sets the type of the document to which the link points;
• rel- sets the status of the document to which the link points in relation to the original document;
• rev- sets the status of the source document in relation to the one to which this link points;
• media- indicates the type of device on which the referenced document will be displayed.

Currently, documents displayed on conventional monitors, on braille monitors for the visually impaired, for printers and speech reproduction devices are supported. And, of course, in addition to these parameters, a set of additional identification parameters common to all tags is used.

It remains for us to consider only one tag used to serve hyperlinks. As we know, we may omit the full URL for hyperlinked documents if the document is located on the same Web site as the original Web page. But it turns out that we can do the same with hyperlinks to Web pages that are part of other sites.

Using the tag we set the base for hyperlinks with shortened href values. Let's try to demonstrate the operation of this mechanism using a simple and illustrative example:

"http://www.w3.org/TR/html4/strict.dtd">



<Р>Text<А href="/pages/birds.gif">Link

As the value of the required parameter href tag we define the document that is the basis for the content of the web pages of our site. And now, if in the body of our HTML document we use a hyperlink with a shortened URL, then the domain name for this URL will not be the name of the original site, but the one specified in the tag ... So in the example, the hyperlink points to a document

c URL www.mysite.com/pages/birds.gif.

It should be clarified that the tag placed in the head of the document between tags and .

And that's all we can talk about using hyperlinks in HTML.

Hypertext is text that contains links to other text. An example is the author's notes on complex definitions or translators' footnotes at the bottom of a book page if it contains text in a foreign language. Internet sites are a complex system of hypertext transitions from one page to another, within the page itself, as well as between unrelated resources. This structure is practical, saves a lot of time, allows the visitor to quickly find the necessary information and not get lost in a large number of transitions.

Insert a hyperlink