Purpose of class attribute in html

Global attributes are attributes common to all HTML elements; they can be used on all elements, though they may have no effect on some elements. Global attributes may be specified on all even those not specified in the standard. That means that any non-standard elements must still permit these attributes, even though using those elements means that the document is no longer HTML5-compliant. For example, HTML5-compliant browsers hide content marked as …, even though is not a valid HTML element. In addition to the basic HTML global attributes, the following global attributes also exist: • xml:lang and xml:base — these are inherited from the XHTML specifications and deprecated, but kept for compatibility purposes. • The ARIA role attribute and the multiple aria-* states and properties, used for ensuring accessibility. • The onabort, onautocomplete, onautocompleteerror, onblur, oncancel, oncanplay, oncanplaythrough, onchange, onclick, onclose, oncontextmenu, oncuechange, ondblclick, ondrag, ondragend, ondragenter, ondragleave, ondragover, ondragstart, ondrop, ondurationchange, onemptied, onended, onerror, onfocus, oninput, oninvalid, onkeydown, onkeypress, onkeyup, onload, onloadeddata, onloadedmetadata, onloadstart, onmousedown, onmouseenter, onmouseleave, onmousemove, onmouseout, onmouseover, onmouseup, onmousewheel, onpause, onplay, onplaying, onprogress, onratechange, onreset, onresize, onscroll, onseeked, onseeking, onselect, onshow, onsort, onstalled, onsubmit, onsuspen...

HTML is designed with extensibility in mind for data that should be associated with a particular element but need not have any defined meaning. data-* attributes allow us to store extra information on standard, semantic HTML elements without other hacks such as non-standard attributes, or extra properties on DOM. Reading the values of these attributes out in getAttribute() with their full HTML name to read them, but the standard defines a simpler way: a DOMStringMap you can read out via a dataset property. To get a data attribute through the dataset object, get the property by the part of the attribute name after data- (note that dashes are converted to camelCase). const article = document . querySelector ( "#electric-cars" ) ; // The following would also work: // const article = document.getElementById("electric-cars") article .dataset .columns ; // "3" article .dataset .indexNumber ; // "12314" article .dataset .parent ; // "cars" Each property is a string and can be read and written. In the above case setting article.dataset.columns = 5 would change that attribute to "5". article[data-columns="3"] You can see all this working together Data attributes can also be stored to contain information that is constantly changing, like scores in a game. Using the CSS selectors and JavaScript access here this allows you to build some nifty effects without having to write your own display routines. See Data values are strings. Number values must be quoted in the selector for the st...

In HTML, it's good to have a lang attribute in , e.g. . How is this useful? If this is used for translation, even if the language is set to English and there are all Chinese text in the document Google Translate detects it as Chinese, not English (this means Google ignores the lang attribute). I am quoting this from Declaring language in HTML Always use a language attribute on the html tag to declare the default language of the text in the page. When the page contains content in another language, add a language attribute to an element surrounding that content. Use the lang attribute for pages served as HTML, and the xml:lang attribute for pages served as XML. For XHTML 1.x and HTML5 polyglot documents, use both together. Use language tags from the Also a good read is Bleh... the quoted content, which is simply an unexplained instruction to use the attribute, doesn't even remotely answer the question (which was WHY to use the attribute and what it does). This is effectively a link-only answer; the only content that's actually relevant to the question is at the 'Why use the language attribute?' link. I'll probably edit this later to shift the actually relevant content into the answer (or feel free to do so yourself). You asked "how is this useful". "The attribute can be used to declare the language of a Web page or a portion of a Web page. This is meant to assist search engine spiders, page formatting and screen reader technology" Source: http://symbolcodes.tlt.psu.edu/web/...

Previous All HTML Attributes Next ❯ Definition and Usage The class attribute specifies one or more classnames for an element. The class attribute is mostly used to point to a class in a style sheet. However, it can also be used by a JavaScript (via the HTML DOM) to make changes to HTML elements with a specified class. Applies to The class attribute is part of the Element Attribute All HTML elements

Warning: This attribute's value is an opaque string: this means that web authors should not rely on it to convey human-readable information (although having your IDs somewhat human-readable can be useful for code comprehension, e.g. consider ticket-18659 versus r45tgfe-freds&$@). An id's value must not contain class attribute, which allows space-separated values, elements can only have one single ID value. Technically, the value for an id attribute may contain any character, except '_', and '-' should be used, and the value for an id attribute should start with a letter. For example, . has a special meaning in CSS (it starts a id. The same applies to the querySelector() and querySelectorAll() parameters, which use the same selector syntax. It is easy to forget to do this, resulting in bugs in your code that could be hard to detect. Similarly, an id starting with a digit (E.g., 1234-322-678) or a hyphen followed by a digit (E.g., -123), though valid in HTML, may lead to problems when used in CSS, JavaScript, and Web APIs: • CSS id starts with a digit or one hyphen immediately followed by a digit, both the hyphen and digit must be escaped in CSS. For example, while id="544-383-3388" and id="-3Pi" are valid in HTML, the id selectors must be escaped. The element with these id values can be targeted in CSS with #\35 44-383-3388 and #\2D \33 pi. • Any valid HTML id value is valid as an attribute selector in CSS and JavaScript. The selectors [id="544-383-3388"] and [id="-3Pi"] ar...

The name attribute identifies the input value if it is sent to a server via a traditional GET or POST of a form. Specific to the example if you had: Click me and you submit the form, the server localhost will receive a content body like: Name=foo which as another post mentions, is usually parsed by a server side language like PHP into something easier to work with. The id attribute identifies the input to the DOM. If you specify an input with no name but an id and try to submit it via a GET or POST it will not be parsed correctly by the server. In an input element, the name attribute defines the name of the control. Only controls that have a name can be “successful”, i.e. may contribute to the form data set sent to a server. Thus, it is indispensable in order to make the value of the control submitted to server-side processing. The id attribute has nothing to do with this; it has its own uses, such as helping to associate a label with the control, as in the example. Consequently, the name attribute is not needed if you need not have the control value submitted. For example, if you have a single submit button like , you don’t need it; but if you have several submit buttons and you need to recognize, server-side, which one was used, you need it. If the form data is not sent to server-side processing but handled only in client-side processing, the name attribute is not used, as you can access the values with other means. In span and div elements, a name attribute is invalid i...

The author selected the Writing CSS selectors most often involves setting a condition and locating the element in the In this tutorial, you will use the id, class, and attribute selectors to scope styles to intentionally written HTML. You will begin by creating an HTML and a CSS file that you will edit throughout the tutorial. You will then add id attributes and use those id values to target styles. You will also add class attributes to elements and use those class values independently and together to create more specific and reusable styles. Lastly, you will use the attribute selector to create styles that match much more specific scenarios than an id or class selector alone can accomplish. • An understanding of CSS’s cascade and specificity features, which you can get by reading • Knowledge of type selectors, combinator selectors, and selector groups, which you can find in • An empty HTML file saved on your local machine as index.html that you can access from your text editor and web browser of choice. To get started, check out our To start working with id, class, and attribute selectors, you will first set up the HTML and CSS code that you will work on through the rest of the tutorial. In this section, you will write out all the necessary HTML and some initial CSS styles that will handle layout and start the visual aesthetic. To begin, open index.html in your text editor. Then, add the following HTML to the file: index.html Next, go to the tag and add a tag to ...