Friday, 29 April 2016

Html attributes

HTML elements can have attributes
Attributes provide additional information about an element
Attributes are always specified in the start tag
Attributes come in name/value pairs like: name="value"
The document language can be declared in the <html> tag.
The language is declared in the lang attribute.
Declaring a language is important for accessibility applications (screen readers) and search engines:
<!DOCTYPE html>
<html lang="en-US">
<body>
<h1>My First Heading</h1>
<p>My first paragraph.</p>
</body>
</html>
HTML paragraphs are defined with the <p> tag.
In this example, the <p> element has a title attribute. The value of the attribute is "About amegingthoughts":
<p title="About amegingthought">
Amegingthought is a web developer's site.
It provides tutorials and references covering
many aspects of web programming,
including HTML, CSS, JavaScript, XML, SQL, PHP, ASP, etc.
</p>
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>
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 specifies an alternative text to be used, when an HTML element cannot be displayed.
The value of the attribute can be read by "screen readers". This way, someone "listening" to the webpage, i.e. a blind person, can "hear" the element.
<img src="w3schools.jpg" alt="W3Schools.com" width="104" height="142">
The HTML5 standard does not require lower case attribute names.
The title attribute can be written with upper or lower case like Title and/or TITLE.
W3C recommends lowercase in HTML4, and demands lowercase for stricter document types like XHTML.
The HTML5 standard does not require quotes around attribute values.
The href attribute, demonstrated above, can be written as:
<a href=http://www.w3schools.com>
W3C recommends quotes in HTML4, and demands quotes for stricter document types like XHTML.
Sometimes it is necessary to use quotes. This will not display correctly, because it contains a space:
<p title=About W3Schools>
Double style quotes are the most common in HTML, but single style can also be used.
In some situations, when the attribute value itself contains double quotes, it is necessary to use single quotes:
<p title='John "ShotGun" Nelson'>
<p title="John 'ShotGun' Nelson">
All HTML elements can have attributes
The HTML title attribute provides additional "tool-tip" information
The HTML href attribute provides address information for links
The HTML width and height attributes provide size information for images
The HTML alt attribute provides text for screen readers
At W3Schools we always use lowercase HTML attribute names
At W3Schools we always quote attributes with double quotes

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