chrome-devtools-frontend

{ "version": 1.1, "tags": [ { "name": "html", "description": { "kind": "markdown", "value": "The html element represents the root of an HTML document." }, "attributes": [ { "name": "manifest", "description": { "kind": "markdown", "value": "Specifies the URI of a resource manifest indicating resources that should be cached locally. See [Using the application cache](https://developer.mozilla.org/en-US/docs/Web/HTML/Using_the_application_cache) for details." } }, { "name": "version", "description": "Specifies the version of the HTML [Document Type Definition](https://developer.mozilla.org/en-US/docs/Glossary/DTD \"Document Type Definition: In HTML, the doctype is the required \"<!DOCTYPE html>\" preamble found at the top of all documents. Its sole purpose is to prevent a browser from switching into so-called “quirks mode” when rendering a document; that is, the \"<!DOCTYPE html>\" doctype ensures that the browser makes a best-effort attempt at following the relevant specifications, rather than using a different rendering mode that is incompatible with some specifications.\") that governs the current document. This attribute is not needed, because it is redundant with the version information in the document type declaration." }, { "name": "xmlns", "description": "Specifies the XML Namespace of the document. Default value is `\"http://www.w3.org/1999/xhtml\"`. This is required in documents parsed with XML parsers, and optional in text/html documents." } ], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.org/docs/Web/HTML/Element/html" } ] }, { "name": "head", "description": { "kind": "markdown", "value": "The head element represents a collection of metadata for the Document." }, "attributes": [ { "name": "profile", "description": "The URIs of one or more metadata profiles, separated by white space." } ], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.org/docs/Web/HTML/Element/head" } ] }, { "name": "title", "description": { "kind": "markdown", "value": "The title element represents the document's title or name. Authors should use titles that identify their documents even when they are used out of context, for example in a user's history or bookmarks, or in search results. The document's title is often different from its first heading, since the first heading does not have to stand alone when taken out of context." }, "attributes": [], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.org/docs/Web/HTML/Element/title" } ] }, { "name": "base", "description": { "kind": "markdown", "value": "The base element allows authors to specify the document base URL for the purposes of resolving relative URLs, and the name of the default browsing context for the purposes of following hyperlinks. The element does not represent any content beyond this information." }, "void": true, "attributes": [ { "name": "href", "description": { "kind": "markdown", "value": "The base URL to be used throughout the document for relative URL addresses. If this attribute is specified, this element must come before any other elements with attributes whose values are URLs. Absolute and relative URLs are allowed." } }, { "name": "target", "valueSet": "target", "description": { "kind": "markdown", "value": "A name or keyword indicating the default location to display the result when hyperlinks or forms cause navigation, for elements that do not have an explicit target reference. It is a name of, or keyword for, a _browsing context_ (for example: tab, window, or inline frame). The following keywords have special meanings:\n\n* `_self`: Load the result into the same browsing context as the current one. This value is the default if the attribute is not specified.\n* `_blank`: Load the result into a new unnamed browsing context.\n* `_parent`: Load the result into the parent browsing context of the current one. If there is no parent, this option behaves the same way as `_self`.\n* `_top`: Load the result into the top-level browsing context (that is, the browsing context that is an ancestor of the current one, and has no parent). If there is no parent, this option behaves the same way as `_self`.\n\nIf this attribute is specified, this element must come before any other elements with attributes whose values are URLs." } } ], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.org/docs/Web/HTML/Element/base" } ] }, { "name": "link", "description": { "kind": "markdown", "value": "The link element allows authors to link their document to other resources." }, "void": true, "attributes": [ { "name": "href", "description": { "kind": "markdown", "value": "This attribute specifies the [URL](https://developer.mozilla.org/en-US/docs/Glossary/URL \"URL: Uniform Resource Locator (URL) is a text string specifying where a resource can be found on the Internet.\") of the linked resource. A URL can be absolute or relative." } }, { "name": "crossorigin", "valueSet": "xo", "description": { "kind": "markdown", "value": "This enumerated attribute indicates whether [CORS](https://developer.mozilla.org/en-US/docs/Glossary/CORS \"CORS: CORS (Cross-Origin Resource Sharing) is a system, consisting of transmitting HTTP headers, that determines whether browsers block frontend JavaScript code from accessing responses for cross-origin requests.\") must be used when fetching the resource. [CORS-enabled images](https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_Enabled_Image) can be reused in the [`<canvas>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/canvas \"Use the HTML <canvas> element with either the canvas scripting API or the WebGL API to draw graphics and animations.\") element without being _tainted_. The allowed values are:\n\n`anonymous`\n\nA cross-origin request (i.e. with an [`Origin`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Origin \"The Origin request header indicates where a fetch originates from. It doesn't include any path information, but only the server name. It is sent with CORS requests, as well as with POST requests. It is similar to the Referer header, but, unlike this header, it doesn't disclose the whole path.\") HTTP header) is performed, but no credential is sent (i.e. no cookie, X.509 certificate, or HTTP Basic authentication). If the server does not give credentials to the origin site (by not setting the [`Access-Control-Allow-Origin`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin \"The Access-Control-Allow-Origin response header indicates whether the response can be shared with requesting code from the given origin.\") HTTP header) the image will be tainted and its usage restricted.\n\n`use-credentials`\n\nA cross-origin request (i.e. with an `Origin` HTTP header) is performed along with a credential sent (i.e. a cookie, certificate, and/or HTTP Basic authentication is performed). If the server does not give credentials to the origin site (through [`Access-Control-Allow-Credentials`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Credentials \"The Access-Control-Allow-Credentials response header tells browsers whether to expose the response to frontend JavaScript code when the request's credentials mode (Request.credentials) is \"include\".\") HTTP header), the resource will be _tainted_ and its usage restricted.\n\nIf the attribute is not present, the resource is fetched without a [CORS](https://developer.mozilla.org/en-US/docs/Glossary/CORS \"CORS: CORS (Cross-Origin Resource Sharing) is a system, consisting of transmitting HTTP headers, that determines whether browsers block frontend JavaScript code from accessing responses for cross-origin requests.\") request (i.e. without sending the `Origin` HTTP header), preventing its non-tainted usage. If invalid, it is handled as if the enumerated keyword **anonymous** was used. See [CORS settings attributes](https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_settings_attributes) for additional information." } }, { "name": "rel", "description": { "kind": "markdown", "value": "This attribute names a relationship of the linked document to the current document. The attribute must be a space-separated list of the [link types values](https://developer.mozilla.org/en-US/docs/Web/HTML/Link_types)." } }, { "name": "media", "description": { "kind": "markdown", "value": "This attribute specifies the media that the linked resource applies to. Its value must be a media type / [media query](https://developer.mozilla.org/en-US/docs/Web/CSS/Media_queries). This attribute is mainly useful when linking to external stylesheets — it allows the user agent to pick the best adapted one for the device it runs on.\n\n**Notes:**\n\n* In HTML 4, this can only be a simple white-space-separated list of media description literals, i.e., [media types and groups](https://developer.mozilla.org/en-US/docs/Web/CSS/@media), where defined and allowed as values for this attribute, such as `print`, `screen`, `aural`, `braille`. HTML5 extended this to any kind of [media queries](https://developer.mozilla.org/en-US/docs/Web/CSS/Media_queries), which are a superset of the allowed values of HTML 4.\n* Browsers not supporting [CSS3 Media Queries](https://developer.mozilla.org/en-US/docs/Web/CSS/Media_queries) won't necessarily recognize the adequate link; do not forget to set fallback links, the restricted set of media queries defined in HTML 4." } }, { "name": "hreflang", "description": { "kind": "markdown", "value": "This attribute indicates the language of the linked resource. It is purely advisory. Allowed values are determined by [BCP47](https://www.ietf.org/rfc/bcp/bcp47.txt). Use this attribute only if the [`href`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#attr-href) attribute is present." } }, { "name": "type", "description": { "kind": "markdown", "value": "This attribute is used to define the type of the content linked to. The value of the attribute should be a MIME type such as **text/html**, **text/css**, and so on. The common use of this attribute is to define the type of stylesheet being referenced (such as **text/css**), but given that CSS is the only stylesheet language used on the web, not only is it possible to omit the `type` attribute, but is actually now recommended practice. It is also used on `rel=\"preload\"` link types, to make sure the browser only downloads file types that it supports." } }, { "name": "sizes", "description": { "kind": "markdown", "value": "This attribute defines the sizes of the icons for visual media contained in the resource. It must be present only if the [`rel`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/link#attr-rel) contains a value of `icon` or a non-standard type such as Apple's `apple-touch-icon`. It may have the following values:\n\n* `any`, meaning that the icon can be scaled to any size as it is in a vector format, like `image/svg+xml`.\n* a white-space separated list of sizes, each in the format `_<width in pixels>_x_<height in pixels>_` or `_<width in pixels>_X_<height in pixels>_`. Each of these sizes must be contained in the resource.\n\n**Note:** Most icon formats are only able to store one single icon; therefore most of the time the [`sizes`](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes#attr-sizes) contains only one entry. MS's ICO format does, as well as Apple's ICNS. ICO is more ubiquitous; you should definitely use it." } }, { "name": "as", "description": "This attribute is only used when `rel=\"preload\"` or `rel=\"prefetch\"` has been set on the `<link>` element. It specifies the type of content being loaded by the `<link>`, which is necessary for content prioritization, request matching, application of correct [content security policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP), and setting of correct [`Accept`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept \"The Accept request HTTP header advertises which content types, expressed as MIME types, the client is able to understand. Using content negotiation, the server then selects one of the proposals, uses it and informs the client of its choice with the Content-Type response header. Browsers set adequate values for this header depending on the context where the request is done: when fetching a CSS stylesheet a different value is set for the request than when fetching an image, video or a script.\") request header." }, { "name": "importance", "description": "Indicates the relative importance of the resource. Priority hints are delegated using the values:" }, { "name": "importance", "description": "**`auto`**: Indicates **no preference**. The browser may use its own heuristics to decide the priority of the resource.\n\n**`high`**: Indicates to the browser that the resource is of **high** priority.\n\n**`low`**: Indicates to the browser that the resource is of **low** priority.\n\n**Note:** The `importance` attribute may only be used for the `<link>` element if `rel=\"preload\"` or `rel=\"prefetch\"` is present." }, { "name": "integrity", "description": "Contains inline metadata — a base64-encoded cryptographic hash of the resource (file) you’re telling the browser to fetch. The browser can use this to verify that the fetched resource has been delivered free of unexpected manipulation. See [Subresource Integrity](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity)." }, { "name": "referrerpolicy", "description": "A string indicating which referrer to use when fetching the resource:\n\n* `no-referrer` means that the [`Referer`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referer \"The Referer request header contains the address of the previous web page from which a link to the currently requested page was followed. The Referer header allows servers to identify where people are visiting them from and may use that data for analytics, logging, or optimized caching, for example.\") header will not be sent.\n* `no-referrer-when-downgrade` means that no [`Referer`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referer \"The Referer request header contains the address of the previous web page from which a link to the currently requested page was followed. The Referer header allows servers to identify where people are visiting them from and may use that data for analytics, logging, or optimized caching, for example.\") header will be sent when navigating to an origin without TLS (HTTPS). This is a user agent’s default behavior, if no policy is otherwise specified.\n* `origin` means that the referrer will be the origin of the page, which is roughly the scheme, the host, and the port.\n* `origin-when-cross-origin` means that navigating to other origins will be limited to the scheme, the host, and the port, while navigating on the same origin will include the referrer's path.\n* `unsafe-url` means that the referrer will include the origin and the path (but not the fragment, password, or username). This case is unsafe because it can leak origins and paths from TLS-protected resources to insecure origins." }, { "name": "title", "description": "The `title` attribute has special semantics on the `<link>` element. When used on a `<link rel=\"stylesheet\">` it defines a [preferred or an alternate stylesheet](https://developer.mozilla.org/en-US/docs/Web/CSS/Alternative_style_sheets). Incorrectly using it may [cause the stylesheet to be ignored](https://developer.mozilla.org/en-US/docs/Correctly_Using_Titles_With_External_Stylesheets)." } ], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.org/docs/Web/HTML/Element/link" } ] }, { "name": "meta", "description": { "kind": "markdown", "value": "The meta element represents various kinds of metadata that cannot be expressed using the title, base, link, style, and script elements." }, "void": true, "attributes": [ { "name": "name", "description": { "kind": "markdown", "value": "This attribute defines the name of a piece of document-level metadata. It should not be set if one of the attributes [`itemprop`](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes#attr-itemprop), [`http-equiv`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-http-equiv) or [`charset`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-charset) is also set.\n\nThis metadata name is associated with the value contained by the [`content`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-content) attribute. The possible values for the name attribute are:\n\n* `application-name` which defines the name of the application running in the web page.\n \n **Note:**\n \n * Browsers may use this to identify the application. It is different from the [`<title>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/title \"The HTML Title element (<title>) defines the document's title that is shown in a browser's title bar or a page's tab.\") element, which usually contain the application name, but may also contain information like the document name or a status.\n * Simple web pages shouldn't define an application-name.\n \n* `author` which defines the name of the document's author.\n* `description` which contains a short and accurate summary of the content of the page. Several browsers, like Firefox and Opera, use this as the default description of bookmarked pages.\n* `generator` which contains the identifier of the software that generated the page.\n* `keywords` which contains words relevant to the page's content separated by commas.\n* `referrer` which controls the [`Referer` HTTP header](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referer) attached to requests sent from the document:\n \n Values for the `content` attribute of `<meta name=\"referrer\">`\n \n `no-referrer`\n \n Do not send a HTTP `Referrer` header.\n \n `origin`\n \n Send the [origin](https://developer.mozilla.org/en-US/docs/Glossary/Origin) of the document.\n \n `no-referrer-when-downgrade`\n \n Send the [origin](https://developer.mozilla.org/en-US/docs/Glossary/Origin) as a referrer to URLs as secure as the current page, (https→https), but does not send a referrer to less secure URLs (https→http). This is the default behaviour.\n \n `origin-when-cross-origin`\n \n Send the full URL (stripped of parameters) for same-origin requests, but only send the [origin](https://developer.mozilla.org/en-US/docs/Glossary/Origin) for other cases.\n \n `same-origin`\n \n A referrer will be sent for [same-site origins](https://developer.mozilla.org/en-US/docs/Web/Security/Same-origin_policy), but cross-origin requests will contain no referrer information.\n \n `strict-origin`\n \n Only send the origin of the document as the referrer to a-priori as-much-secure destination (HTTPS->HTTPS), but don't send it to a less secure destination (HTTPS->HTTP).\n \n `strict-origin-when-cross-origin`\n \n Send a full URL when performing a same-origin request, only send the origin of the document to a-priori as-much-secure destination (HTTPS->HTTPS), and send no header to a less secure destination (HTTPS->HTTP).\n \n `unsafe-URL`\n \n Send the full URL (stripped of parameters) for same-origin or cross-origin requests.\n \n **Notes:**\n \n * Some browsers support the deprecated values of `always`, `default`, and `never` for referrer.\n * Dynamically inserting `<meta name=\"referrer\">` (with [`document.write`](https://developer.mozilla.org/en-US/docs/Web/API/Document/write) or [`appendChild`](https://developer.mozilla.org/en-US/docs/Web/API/Node/appendChild)) makes the referrer behaviour unpredictable.\n * When several conflicting policies are defined, the no-referrer policy is applied.\n \n\nThis attribute may also have a value taken from the extended list defined on [WHATWG Wiki MetaExtensions page](https://wiki.whatwg.org/wiki/MetaExtensions). Although none have been formally accepted yet, a few commonly used names are:\n\n* `creator` which defines the name of the creator of the document, such as an organization or institution. If there are more than one, several [`<meta>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta \"The HTML <meta> element represents metadata that cannot be represented by other HTML meta-related elements, like <base>, <link>, <script>, <style> or <title>.\") elements should be used.\n* `googlebot`, a synonym of `robots`, is only followed by Googlebot (the indexing crawler for Google).\n* `publisher` which defines the name of the document's publisher.\n* `robots` which defines the behaviour that cooperative crawlers, or \"robots\", should use with the page. It is a comma-separated list of the values below:\n \n Values for the content of `<meta name=\"robots\">`\n \n Value\n \n Description\n \n Used by\n \n `index`\n \n Allows the robot to index the page (default).\n \n All\n \n `noindex`\n \n Requests the robot to not index the page.\n \n All\n \n `follow`\n \n Allows the robot to follow the links on the page (default).\n \n All\n \n `nofollow`\n \n Requests the robot to not follow the links on the page.\n \n All\n \n `none`\n \n Equivalent to `noindex, nofollow`\n \n [Google](https://support.google.com/webmasters/answer/79812)\n \n `noodp`\n \n Prevents using the [Open Directory Project](https://www.dmoz.org/) description, if any, as the page description in search engine results.\n \n [Google](https://support.google.com/webmasters/answer/35624#nodmoz), [Yahoo](https://help.yahoo.com/kb/search-for-desktop/meta-tags-robotstxt-yahoo-search-sln2213.html#cont5), [Bing](https://www.bing.com/webmaster/help/which-robots-metatags-does-bing-support-5198d240)\n \n `noarchive`\n \n Requests the search engine not to cache the page content.\n \n [Google](https://developers.google.com/webmasters/control-crawl-index/docs/robots_meta_tag#valid-indexing--serving-directives), [Yahoo](https://help.yahoo.com/kb/search-for-desktop/SLN2213.html), [Bing](https://www.bing.com/webmaster/help/which-robots-metatags-does-bing-support-5198d240)\n \n `nosnippet`\n \n Prevents displaying any description of the page in search engine results.\n \n [Google](https://developers.google.com/webmasters/control-crawl-index/docs/robots_meta_tag#valid-indexing--serving-directives), [Bing](https://www.bing.com/webmaster/help/which-robots-metatags-does-bing-support-5198d240)\n \n `noimageindex`\n \n Requests this page not to appear as the referring page of an indexed image.\n \n [Google](https://developers.google.com/webmasters/control-crawl-index/docs/robots_meta_tag#valid-indexing--serving-directives)\n \n `nocache`\n \n Synonym of `noarchive`.\n \n [Bing](https://www.bing.com/webmaster/help/which-robots-metatags-does-bing-support-5198d240)\n \n **Notes:**\n \n * Only cooperative robots follow these rules. Do not expect to prevent e-mail harvesters with them.\n * The robot still needs to access the page in order to read these rules. To prevent bandwidth consumption, use a _[robots.txt](https://developer.mozilla.org/en-US/docs/Glossary/robots.txt \"robots.txt: Robots.txt is a file which is usually placed in the root of any website. It decides whether crawlers are permitted or forbidden access to the web site.\")_ file.\n * If you want to remove a page, `noindex` will work, but only after the robot visits the page again. Ensure that the `robots.txt` file is not preventing revisits.\n * Some values are mutually exclusive, like `index` and `noindex`, or `follow` and `nofollow`. In these cases the robot's behaviour is undefined and may vary between them.\n * Some crawler robots, like Google, Yahoo and Bing, support the same values for the HTTP header `X-Robots-Tag`; this allows non-HTML documents like images to use these rules.\n \n* `slurp`, is a synonym of `robots`, but only for Slurp - the crawler for Yahoo Search.\n* `viewport`, which gives hints about the size of the initial size of the [viewport](https://developer.mozilla.org/en-US/docs/Glossary/viewport \"viewport: A viewport represents a polygonal (normally rectangular) area in computer graphics that is currently being viewed. In web browser terms, it refers to the part of the document you're viewing which is currently visible in its window (or the screen, if the document is being viewed in full screen mode). Content outside the viewport is not visible onscreen until scrolled into view.\"). Used by mobile devices only.\n \n Values for the content of `<meta name=\"viewport\">`\n \n Value\n \n Possible subvalues\n \n Description\n \n `width`\n \n A positive integer number, or the text `device-width`\n \n Defines the pixel width of the viewport that you want the web site to be rendered at.\n \n `height`\n \n A positive integer, or the text `device-height`\n \n Defines the height of the viewport. Not used by any browser.\n \n `initial-scale`\n \n A positive number between `0.0` and `10.0`\n \n Defines the ratio between the device width (`device-width` in portrait mode or `device-height` in landscape mode) and the viewport size.\n \n `maximum-scale`\n \n A positive number between `0.0` and `10.0`\n \n Defines the maximum amount to zoom in. It must be greater or equal to the `minimum-scale` or the behaviour is undefined. Browser settings can ignore this rule and iOS10+ ignores it by default.\n \n `minimum-scale`\n \n A positive number between `0.0` and `10.0`\n \n Defines the minimum zoom level. It must be smaller or equal to the `maximum-scale` or the behaviour is undefined. Browser settings can ignore this rule and iOS10+ ignores it by default.\n \n `user-scalable`\n \n `yes` or `no`\n \n If set to `no`, the user is not able to zoom in the webpage. The default is `yes`. Browser settings can ignore this rule, and iOS10+ ignores it by default.\n \n Specification\n \n Status\n \n Comment\n \n [CSS Device Adaptation \n The definition of '<meta name=\"viewport\">' in that specification.](https://drafts.csswg.org/css-device-adapt/#viewport-meta)\n \n Working Draft\n \n Non-normatively describes the Viewport META element\n \n See also: [`@viewport`](https://developer.mozilla.org/en-US/docs/Web/CSS/@viewport \"The @viewport CSS at-rule lets you configure the viewport through which the document is viewed. It's primarily used for mobile devices, but is also used by desktop browsers that support features like \"snap to edge\" (such as Microsoft Edge).\")\n \n **Notes:**\n \n * Though unstandardized, this declaration is respected by most mobile browsers due to de-facto dominance.\n * The default values may vary between devices and browsers.\n * To learn about this declaration in Firefox for Mobile, see [this article](https://developer.mozilla.org/en-US/docs/Mobile/Viewport_meta_tag \"Mobile/Viewport meta tag\")." } }, { "name": "http-equiv", "description": { "kind": "markdown", "value": "Defines a pragma directive. The attribute is named `**http-equiv**(alent)` because all the allowed values are names of particular HTTP headers:\n\n* `\"content-language\"` \n Defines the default language of the page. It can be overridden by the [lang](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/lang) attribute on any element.\n \n **Warning:** Do not use this value, as it is obsolete. Prefer the `lang` attribute on the [`<html>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/html \"The HTML <html> element represents the root (top-level element) of an HTML document, so it is also referred to as the root element. All other elements must be descendants of this element.\") element.\n \n* `\"content-security-policy\"` \n Allows page authors to define a [content policy](https://developer.mozilla.org/en-US/docs/Web/Security/CSP/CSP_policy_directives) for the current page. Content policies mostly specify allowed server origins and script endpoints which help guard against cross-site scripting attacks.\n* `\"content-type\"` \n Defines the [MIME type](https://developer.mozilla.org/en-US/docs/Glossary/MIME_type) of the document, followed by its character encoding. It follows the same syntax as the HTTP `content-type` entity-header field, but as it is inside a HTML page, most values other than `text/html` are impossible. Therefore the valid syntax for its `content` is the string '`text/html`' followed by a character set with the following syntax: '`; charset=_IANAcharset_`', where `IANAcharset` is the _preferred MIME name_ for a character set as [defined by the IANA.](https://www.iana.org/assignments/character-sets)\n \n **Warning:** Do not use this value, as it is obsolete. Use the [`charset`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-charset) attribute on the [`<meta>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta \"The HTML <meta> element represents metadata that cannot be represented by other HTML meta-related elements, like <base>, <link>, <script>, <style> or <title>.\") element.\n \n **Note:** As [`<meta>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta \"The HTML <meta> element represents metadata that cannot be represented by other HTML meta-related elements, like <base>, <link>, <script>, <style> or <title>.\") can't change documents' types in XHTML or HTML5's XHTML serialization, never set the MIME type to an XHTML MIME type with `<meta>`.\n \n* `\"refresh\"` \n This instruction specifies:\n * The number of seconds until the page should be reloaded - only if the [`content`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-content) attribute contains a positive integer.\n * The number of seconds until the page should redirect to another - only if the [`content`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-content) attribute contains a positive integer followed by the string '`;url=`', and a valid URL.\n* `\"set-cookie\"` \n Defines a [cookie](https://developer.mozilla.org/en-US/docs/cookie) for the page. Its content must follow the syntax defined in the [IETF HTTP Cookie Specification](https://tools.ietf.org/html/draft-ietf-httpstate-cookie-14).\n \n **Warning:** Do not use this instruction, as it is obsolete. Use the HTTP header [`Set-Cookie`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie) instead." } }, { "name": "content", "description": { "kind": "markdown", "value": "This attribute contains the value for the [`http-equiv`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-http-equiv) or [`name`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-name) attribute, depending on which is used." } }, { "name": "charset", "description": { "kind": "markdown", "value": "This attribute declares the page's character encoding. It must contain a [standard IANA MIME name for character encodings](https://www.iana.org/assignments/character-sets). Although the standard doesn't request a specific encoding, it suggests:\n\n* Authors are encouraged to use [`UTF-8`](https://developer.mozilla.org/en-US/docs/Glossary/UTF-8).\n* Authors should not use ASCII-incompatible encodings to avoid security risk: browsers not supporting them may interpret harmful content as HTML. This happens with the `JIS_C6226-1983`, `JIS_X0212-1990`, `HZ-GB-2312`, `JOHAB`, the ISO-2022 family and the EBCDIC family.\n\n**Note:** ASCII-incompatible encodings are those that don't map the 8-bit code points `0x20` to `0x7E` to the `0x0020` to `0x007E` Unicode code points)\n\n* Authors **must not** use `CESU-8`, `UTF-7`, `BOCU-1` and/or `SCSU` as [cross-site scripting](https://developer.mozilla.org/en-US/docs/Glossary/Cross-site_scripting) attacks with these encodings have been demonstrated.\n* Authors should not use `UTF-32` because not all HTML5 encoding algorithms can distinguish it from `UTF-16`.\n\n**Notes:**\n\n* The declared character encoding must match the one the page was saved with to avoid garbled characters and security holes.\n* The [`<meta>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta \"The HTML <meta> element represents metadata that cannot be represented by other HTML meta-related elements, like <base>, <link>, <script>, <style> or <title>.\") element declaring the encoding must be inside the [`<head>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/head \"The HTML <head> element provides general information (metadata) about the document, including its title and links to its scripts and style sheets.\") element and **within the first 1024 bytes** of the HTML as some browsers only look at those bytes before choosing an encoding.\n* This [`<meta>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta \"The HTML <meta> element represents metadata that cannot be represented by other HTML meta-related elements, like <base>, <link>, <script>, <style> or <title>.\") element is only one part of the [algorithm to determine a page's character set](https://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#encoding-sniffing-algorithm \"Algorithm charset page\"). The [`Content-Type` header](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type) and any [Byte-Order Marks](https://developer.mozilla.org/en-US/docs/Glossary/Byte-Order_Mark \"The definition of that term (Byte-Order Marks) has not been written yet; please consider contributing it!\") override this element.\n* It is strongly recommended to define the character encoding. If a page's encoding is undefined, cross-scripting techniques are possible, such as the [`UTF-7` fallback cross-scripting technique](https://code.google.com/p/doctype-mirror/wiki/ArticleUtf7).\n* The [`<meta>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta \"The HTML <meta> element represents metadata that cannot be represented by other HTML meta-related elements, like <base>, <link>, <script>, <style> or <title>.\") element with a `charset` attribute is a synonym for the pre-HTML5 `<meta http-equiv=\"Content-Type\" content=\"text/html; charset=_IANAcharset_\">`, where _`IANAcharset`_ contains the value of the equivalent [`charset`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-charset) attribute. This syntax is still allowed, although no longer recommended." } }, { "name": "scheme", "description": "This attribute defines the scheme in which metadata is described. A scheme is a context leading to the correct interpretations of the [`content`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#attr-content) value, like a format.\n\n**Warning:** Do not use this value, as it is obsolete. There is no replacement as there was no real usage for it." } ], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.org/docs/Web/HTML/Element/meta" } ] }, { "name": "style", "description": { "kind": "markdown", "value": "The style element allows authors to embed style information in their documents. The style element is one of several inputs to the styling processing model. The element does not represent content for the user." }, "attributes": [ { "name": "media", "description": { "kind": "markdown", "value": "This attribute defines which media the style should be applied to. Its value is a [media query](https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Media_queries), which defaults to `all` if the attribute is missing." } }, { "name": "nonce", "description": { "kind": "markdown", "value": "A cryptographic nonce (number used once) used to whitelist inline styles in a [style-src Content-Security-Policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/style-src). The server must generate a unique nonce value each time it transmits a policy. It is critical to provide a nonce that cannot be guessed as bypassing a resource’s policy is otherwise trivial." } }, { "name": "type", "description": { "kind": "markdown", "value": "This attribute defines the styling language as a MIME type (charset should not be specified). This attribute is optional and defaults to `text/css` if it is not specified — there is very little reason to include this in modern web documents." } }, { "name": "scoped", "valueSet": "v" }, { "name": "title", "description": "This attribute specifies [alternative style sheet](https://developer.mozilla.org/en-US/docs/Web/CSS/Alternative_style_sheets) sets." } ], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.org/docs/Web/HTML/Element/style" } ] }, { "name": "body", "description": { "kind": "markdown", "value": "The body element represents the content of the document." }, "attributes": [ { "name": "onafterprint", "description": { "kind": "markdown", "value": "Function to call after the user has printed the document." } }, { "name": "onbeforeprint", "description": { "kind": "markdown", "value": "Function to call when the user requests printing of the document." } }, { "name": "onbeforeunload", "description": { "kind": "markdown", "value": "Function to call when the document is about to be unloaded." } }, { "name": "onhashchange", "description": { "kind": "markdown", "value": "Function to call when the fragment identifier part (starting with the hash (`'#'`) character) of the document's current address has changed." } }, { "name": "onlanguagechange", "description": { "kind": "markdown", "value": "Function to call when the preferred languages changed." } }, { "name": "onmessage", "description": { "kind": "markdown", "value": "Function to call when the document has received a message." } }, { "name": "onoffline", "description": { "kind": "markdown", "value": "Function to call when network communication has failed." } }, { "name": "ononline", "description": { "kind": "markdown", "value": "Function to call when network communication has been restored." } }, { "name": "onpagehide" }, { "name": "onpageshow" }, { "name": "onpopstate", "description": { "kind": "markdown", "value": "Function to call when the user has navigated session history." } }, { "name": "onstorage", "description": { "kind": "markdown", "value": "Function to call when the storage area has changed." } }, { "name": "onunload", "description": { "kind": "markdown", "value": "Function to call when the document is going away." } }, { "name": "alink", "description": "Color of text for hyperlinks when selected. _This method is non-conforming, use CSS [`color`](https://developer.mozilla.org/en-US/docs/Web/CSS/color \"The color CSS property sets the foreground color value of an element's text and text decorations, and sets the currentcolor value.\") property in conjunction with the [`:active`](https://developer.mozilla.org/en-US/docs/Web/CSS/:active \"The :active CSS pseudo-class represents an element (such as a button) that is being activated by the user.\") pseudo-class instead._" }, { "name": "background", "description": "URI of a image to use as a background. _This method is non-conforming, use CSS [`background`](https://developer.mozilla.org/en-US/docs/Web/CSS/background \"The background shorthand CSS property sets all background style properties at once, such as color, image, origin and size, or repeat method.\") property on the element instead._" }, { "name": "bgcolor", "description": "Background color for the document. _This method is non-conforming, use CSS [`background-color`](https://developer.mozilla.org/en-US/docs/Web/CSS/background-color \"The background-color CSS property sets the background color of an element.\") property on the element instead._" }, { "name": "bottommargin", "description": "The margin of the bottom of the body. _This method is non-conforming, use CSS [`margin-bottom`](https://developer.mozilla.org/en-US/docs/Web/CSS/margin-bottom \"The margin-bottom CSS property sets the margin area on the bottom of an element. A positive value places it farther from its neighbors, while a negative value places it closer.\") property on the element instead._" }, { "name": "leftmargin", "description": "The margin of the left of the body. _This method is non-conforming, use CSS [`margin-left`](https://developer.mozilla.org/en-US/docs/Web/CSS/margin-left \"The margin-left CSS property sets the margin area on the left side of an element. A positive value places it farther from its neighbors, while a negative value places it closer.\") property on the element instead._" }, { "name": "link", "description": "Color of text for unvisited hypertext links. _This method is non-conforming, use CSS [`color`](https://developer.mozilla.org/en-US/docs/Web/CSS/color \"The color CSS property sets the foreground color value of an element's text and text decorations, and sets the currentcolor value.\") property in conjunction with the [`:link`](https://developer.mozilla.org/en-US/docs/Web/CSS/:link \"The :link CSS pseudo-class represents an element that has not yet been visited. It matches every unvisited <a>, <area>, or <link> element that has an href attribute.\") pseudo-class instead._" }, { "name": "onblur", "description": "Function to call when the document loses focus." }, { "name": "onerror", "description": "Function to call when the document fails to load properly." }, { "name": "onfocus", "description": "Function to call when the document receives focus." }, { "name": "onload", "description": "Function to call when the document has finished loading." }, { "name": "onredo", "description": "Function to call when the user has moved forward in undo transaction history." }, { "name": "onresize", "description": "Function to call when the document has been resized." }, { "name": "onundo", "description": "Function to call when the user has moved backward in undo transaction history." }, { "name": "rightmargin", "description": "The margin of the right of the body. _This method is non-conforming, use CSS [`margin-right`](https://developer.mozilla.org/en-US/docs/Web/CSS/margin-right \"The margin-right CSS property sets the margin area on the right side of an element. A positive value places it farther from its neighbors, while a negative value places it closer.\") property on the element instead._" }, { "name": "text", "description": "Foreground color of text. _This method is non-conforming, use CSS [`color`](https://developer.mozilla.org/en-US/docs/Web/CSS/color \"The color CSS property sets the foreground color value of an element's text and text decorations, and sets the currentcolor value.\") property on the element instead._" }, { "name": "topmargin", "description": "The margin of the top of the body. _This method is non-conforming, use CSS [`margin-top`](https://developer.mozilla.org/en-US/docs/Web/CSS/margin-top \"The margin-top CSS property sets the margin area on the top of an element. A positive value places it farther from its neighbors, while a negative value places it closer.\") property on the element instead._" }, { "name": "vlink", "description": "Color of text for visited hypertext links. _This method is non-conforming, use CSS [`color`](https://developer.mozilla.org/en-US/docs/Web/CSS/color \"The color CSS property sets the foreground color value of an element's text and text decorations, and sets the currentcolor value.\") property in conjunction with the [`:visited`](https://developer.mozilla.org/en-US/docs/Web/CSS/:visited \"The :visited CSS pseudo-class represents links that the user has already visited. For privacy reasons, the styles that can be modified using this selector are very limited.\") pseudo-class instead._" } ], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.org/docs/Web/HTML/Element/body" } ] }, { "name": "article", "description": { "kind": "markdown", "value": "The article element represents a complete, or self-contained, composition in a document, page, application, or site and that is, in principle, independently distributable or reusable, e.g. in syndication. This could be a forum post, a magazine or newspaper article, a blog entry, a user-submitted comment, an interactive widget or gadget, or any other independent item of content. Each article should be identified, typically by including a heading (h1–h6 element) as a child of the article element." }, "attributes": [], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.org/docs/Web/HTML/Element/article" } ] }, { "name": "section", "description": { "kind": "markdown", "value": "The section element represents a generic section of a document or application. A section, in this context, is a thematic grouping of content. Each section should be identified, typically by including a heading ( h1- h6 element) as a child of the section element." }, "attributes": [], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.org/docs/Web/HTML/Element/section" } ] }, { "name": "nav", "description": { "kind": "markdown", "value": "The nav element represents a section of a page that links to other pages or to parts within the page: a section with navigation links." }, "attributes": [], "references": [ { "name": "MDN Reference", "url": "https://developer.mozilla.or