HTML5 development

Place media queries as close to their relevant rule sets whenever possible.

Possible values are: off: The user must explicitly enter a value into this field for every use, or the document provides its own auto-completion method. The browser does not automatically complete the entry. on: The browser is allowed to automatically complete the value based on values that the user has entered during previous uses, however on does not provide any further information about what kind of data the user might be expected to enter. name: Full name. honorific-prefix: Prefix or title (e.g. "Mr.", "Ms.", "Dr.", "Mlle"). given-name: First name. additional-name: Middle name. family-name: Last name.

<input type="number"> elements do not support use of the pattern attribute for making entered values conform to a specific regex pattern.

inputs of type number support these attributes

The value of input elements whose type attributes are in the Text, Search, URL, or E-mail states and that are mutable (i.e. that do not have the readonly attribute specified and that are not disabled).The value of textarea elements that do not have a readonly attribute and that are not disabled.

Otherwise, if there is an ancestor element with a spellcheck content attribute that is not in the default state, then: if the nearest such ancestor's spellcheck content attribute is in the true state, then checking is enabled; otherwise, checking is disabled.

When a value is present, a gray x control shows up on the right of the input in IE, Chrome, Safari and Opera (but not Firefox or Chrome on Android) which can be clicked to clear the value.

The :required attribute works on radio buttons. If you put required on one radio button (or all), that particular group of radio buttons will be required. On checkboxes, makes each individual checkbox required (to be checked).

New Input attributes <input type="text" "new input attribute"/> Placeholder Autofocus Required

MP3 was also covered by a bunch of patents, so you had to license it for a fair bit of money; those patents have finally expired now. Ogg and Vorbis have always been free (and the reference implementation available under an LGPL and later BSD license).

Besides the data- prefix, the name of a valid custom data attribute must contain only letters, numbers, hyphen (-), dot (.), colon (:) or underscore (_). It cannot contain capital letters.

A general rule is that the section element is appropriate only if the element’s contents would be listed explicitly in the document’s outline.