Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://html.spec.whatwg.org/multipage/embedded-content.html below:

HTML Standard

Living Standard — Last Updated 9 May 2025

1. 1. 4.8 Embedded content
      1. 4.8.1 The picture element
      2. 4.8.2 The source element
      3. 4.8.3 The img element

Element/picture

Support in all current engines.

Firefox38+Safari9.1+Chrome38+

HTMLPictureElement

Support in all current engines.

Firefox38+Safari9.1+Chrome38+

Categories:

Flow content.

Phrasing content.

Embedded content.

Palpable content.

Contexts in which this element can be used:

Where embedded content is expected.

Content model:

Zero or more source elements, followed by one img element, optionally intermixed with script-supporting elements.

Tag omission in text/html:

Neither tag is omissible.

Content attributes:

Global attributes

Accessibility considerations:

For authors.

For implementers.

DOM interface:

[Exposed=Window]
interface HTMLPictureElement : HTMLElement {
  [HTMLConstructor] constructor();
};

The picture element is a container which provides multiple sources to its contained img element to allow authors to declaratively control or give hints to the user agent about which image resource to use, based on the screen pixel density, viewport size, image format, and other factors. It represents its children.

The picture element is somewhat different from the similar-looking video and audio elements. While all of them contain source elements, the source element's src attribute has no meaning when the element is nested within a picture element, and the resource selection algorithm is different. Also, the picture element itself does not display anything; it merely provides a context for its contained img element that enables it to choose from multiple URLs.

Element/source

Support in all current engines.

Firefox3.5+Safari3.1+Chrome3+

HTMLSourceElement

Support in all current engines.

Firefox3.5+Safari3.1+Chrome3+

Categories:

None.

Contexts in which this element can be used:

As a child of a picture element, before the img element.

As a child of a media element, before any flow content or track elements.

Content model:

Nothing.

Tag omission in text/html:

No end tag.

Content attributes:

Global attributes

type — Type of embedded resource

media — Applicable media

src (in audio or video) — Address of the resource

srcset (in picture) — Images to use in different situations, e.g., high-resolution displays, small monitors, etc.

sizes (in picture) — Image sizes for different page layouts

width (in picture) — Horizontal dimension

height (in picture) — Vertical dimension

Accessibility considerations:

For authors.

For implementers.

DOM interface:

[Exposed=Window]
interface HTMLSourceElement : HTMLElement {
  [HTMLConstructor] constructor();

  [CEReactions] attribute USVString src;
  [CEReactions] attribute DOMString type;
  [CEReactions] attribute USVString srcset;
  [CEReactions] attribute DOMString sizes;
  [CEReactions] attribute DOMString media;
  [CEReactions] attribute unsigned long width;
  [CEReactions] attribute unsigned long height;
};

The source element allows authors to specify multiple alternative source sets for img elements or multiple alternative media resources for media elements. It does not represent anything on its own.

The type attribute may be present. If present, the value must be a valid MIME type string.

The media attribute may also be present. If present, the value must contain a valid media query list. The user agent will skip to the next source element if the value does not match the environment.

The media attribute is only evaluated once during the resource selection algorithm for media elements. In contrast, when using the picture element, the user agent will react to changes in the environment.

The remainder of the requirements depend on whether the parent is a picture element or a media element:

The source element's parent is a picture element

The srcset attribute must be present, and is a srcset attribute.

The srcset attribute contributes the image sources to the source set, if the source element is selected.

If the srcset attribute has any image candidate strings using a width descriptor, the sizes attribute may also be present. If, additionally, the following sibling img element does not allow auto-sizes, the sizes attribute must be present. The sizes attribute is a sizes attribute, which contributes the source size to the source set, if the source element is selected.

If the img element allows auto-sizes, then the sizes attribute can be omitted on previous sibling source elements. In such cases, it is equivalent to specifying auto.

The source element supports dimension attributes. The img element can use the width and height attributes of a source element, instead of those on the img element itself, to determine its rendered dimensions and aspect-ratio, as defined in the Rendering section.

The type attribute gives the type of the images in the source set, to allow the user agent to skip to the next source element if it does not support the given type.

If the type attribute is not specified, the user agent will not select a different source element if it finds that it does not support the image format after fetching it.

When a source element has a following sibling source element or img element with a srcset attribute specified, it must have at least one of the following:

• A media attribute specified with a value that, after stripping leading and trailing ASCII whitespace, is not the empty string and is not an ASCII case-insensitive match for the string "all".

• A type attribute specified.

The src attribute must not be present.

The source element's parent is a media element

The src attribute gives the URL of the media resource. The value must be a valid non-empty URL potentially surrounded by spaces. This attribute must be present.

The type attribute gives the type of the media resource, to help the user agent determine if it can play this media resource before fetching it. The codecs parameter, which certain MIME types define, might be necessary to specify exactly how the resource is encoded. [RFC6381]

Dynamically modifying a source element's src or type attribute when the element is already inserted in a video or audio element will have no effect. To change what is playing, just use the src attribute on the media element directly, possibly making use of the canPlayType() method to pick from amongst available resources. Generally, manipulating source elements manually after the document has been parsed is an unnecessarily complicated approach.

The following list shows some examples of how to use the codecs= MIME parameter in the type attribute.

H.264 Constrained baseline profile video (main and extended video compatible) level 3 and Low-Complexity AAC audio in MP4 container

<source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'>

H.264 Extended profile video (baseline-compatible) level 3 and Low-Complexity AAC audio in MP4 container

<source src='video.mp4' type='video/mp4; codecs="avc1.58A01E, mp4a.40.2"'>

H.264 Main profile video level 3 and Low-Complexity AAC audio in MP4 container

<source src='video.mp4' type='video/mp4; codecs="avc1.4D401E, mp4a.40.2"'>

H.264 'High' profile video (incompatible with main, baseline, or extended profiles) level 3 and Low-Complexity AAC audio in MP4 container

<source src='video.mp4' type='video/mp4; codecs="avc1.64001E, mp4a.40.2"'>

MPEG-4 Visual Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container

<source src='video.mp4' type='video/mp4; codecs="mp4v.20.8, mp4a.40.2"'>

MPEG-4 Advanced Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container

<source src='video.mp4' type='video/mp4; codecs="mp4v.20.240, mp4a.40.2"'>

MPEG-4 Visual Simple Profile Level 0 video and AMR audio in 3GPP container

<source src='video.3gp' type='video/3gpp; codecs="mp4v.20.8, samr"'>

Theora video and Vorbis audio in Ogg container

<source src='video.ogv' type='video/ogg; codecs="theora, vorbis"'>

Theora video and Speex audio in Ogg container

<source src='video.ogv' type='video/ogg; codecs="theora, speex"'>

Vorbis audio alone in Ogg container

<source src='audio.ogg' type='audio/ogg; codecs=vorbis'>

Speex audio alone in Ogg container

<source src='audio.spx' type='audio/ogg; codecs=speex'>

FLAC audio alone in Ogg container

<source src='audio.oga' type='audio/ogg; codecs=flac'>

Dirac video and Vorbis audio in Ogg container

<source src='video.ogv' type='video/ogg; codecs="dirac, vorbis"'>

The srcset and sizes attributes must not be present.

The source HTML element insertion steps, given insertedNode, are:

1. Let parent be insertedNode's parent.

2. If parent is a media element that has no src attribute and whose networkState has the value NETWORK_EMPTY, then invoke that media element's resource selection algorithm.

3. If parent is a picture element, then for each child of parent's children, if child is an img element, then count this as a relevant mutation for child.

The source HTML element moving steps, given movedNode and oldParent, are:

1. If oldParent is a picture element, then for each child of oldParent's children, if child is an img element, then count this as a relevant mutation for child.

The source HTML element removing steps, given removedNode and oldParent, are:

1. If oldParent is a picture element, then for each child of oldParent's children, if child is an img element, then count this as a relevant mutation for child.

The IDL attributes src, type, srcset, sizes, and media must reflect the respective content attributes of the same name.

If the author isn't sure if user agents will all be able to render the media resources provided, the author can listen to the error event on the last source element and trigger fallback behavior:

<script>
 function fallback(video) {
   // replace <video> with its contents
   while (video.hasChildNodes()) {
     if (video.firstChild instanceof HTMLSourceElement)
       video.removeChild(video.firstChild);
     else
       video.parentNode.insertBefore(video.firstChild, video);
   }
   video.parentNode.removeChild(video);
 }
</script>
<video controls autoplay>
 <source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'>
 <source src='video.ogv' type='video/ogg; codecs="theora, vorbis"'
         onerror="fallback(parentNode)">
 ...
</video>

Element/img

Support in all current engines.

Firefox1+Safari1+Chrome1+

HTMLImageElement

Support in all current engines.

Firefox1+Safari1+Chrome1+

Categories:

Flow content.

Phrasing content.

Embedded content.

Form-associated element.

If the element has a usemap attribute: Interactive content.

Palpable content.

Contexts in which this element can be used:

Where embedded content is expected.

As a child of a picture element, after all source elements.

Content model:

Nothing.

Tag omission in text/html:

No end tag.

Content attributes:

Global attributes

alt — Replacement text for use when images are not available

src — Address of the resource

srcset — Images to use in different situations, e.g., high-resolution displays, small monitors, etc.

sizes — Image sizes for different page layouts

crossorigin — How the element handles crossorigin requests

usemap — Name of image map to use

ismap — Whether the image is a server-side image map

width — Horizontal dimension

height — Vertical dimension

referrerpolicy — Referrer policy for fetches initiated by the element

decoding — Decoding hint to use when processing this image for presentation

loading — Used when determining loading deferral

fetchpriority — Sets the priority for fetches initiated by the element

Accessibility considerations:

If the element has a non-empty alt attribute: for authors; for implementers.

Otherwise: for authors; for implementers.

DOM interface:

[Exposed=Window,
 LegacyFactoryFunction=Image(optional unsigned long width, optional unsigned long height)]
interface HTMLImageElement : HTMLElement {
  [HTMLConstructor] constructor();

  [CEReactions] attribute DOMString alt;
  [CEReactions] attribute USVString src;
  [CEReactions] attribute USVString srcset;
  [CEReactions] attribute DOMString sizes;
  [CEReactions] attribute DOMString? crossOrigin;
  [CEReactions] attribute DOMString useMap;
  [CEReactions] attribute boolean isMap;
  [CEReactions] attribute unsigned long width;
  [CEReactions] attribute unsigned long height;
  readonly attribute unsigned long naturalWidth;
  readonly attribute unsigned long naturalHeight;
  readonly attribute boolean complete;
  readonly attribute USVString currentSrc;
  [CEReactions] attribute DOMString referrerPolicy;
  [CEReactions] attribute DOMString decoding;
  [CEReactions] attribute DOMString loading;
  [CEReactions] attribute DOMString fetchPriority;

  Promise<undefined> decode();

  // also has obsolete members
};

An img element represents an image.

An img element has a dimension attribute source, initially set to the element itself.

HTMLImageElement/src

Support in all current engines.

Firefox1+Safari3+Chrome1+

Element/img#attr-srcset

Support in all current engines.

Firefox38+Safari8+Chrome34+

The image given by the src and srcset attributes, and any previous sibling source elements' srcset attributes if the parent is a picture element, is the embedded content; the value of the alt attribute provides equivalent content for those who cannot process images or who have image loading disabled (i.e. it is the img element's fallback content).

The requirements on the alt attribute's value are described in a separate section.

The src attribute must be present, and must contain a valid non-empty URL potentially surrounded by spaces referencing a non-interactive, optionally animated, image resource that is neither paged nor scripted.

The requirements above imply that images can be static bitmaps (e.g. PNGs, GIFs, JPEGs), single-page vector documents (single-page PDFs, XML files with an SVG document element), animated bitmaps (APNGs, animated GIFs), animated vector graphics (XML files with an SVG document element that use declarative SMIL animation), and so forth. However, these definitions preclude SVG files with script, multipage PDF files, interactive MNG files, HTML documents, plain text documents, and the like. [PNG] [GIF] [JPEG] [PDF] [XML] [APNG] [SVG] [MNG]

The srcset attribute may also be present, and is a srcset attribute.

The srcset attribute and the src attribute (if width descriptors are not used) contribute the image sources to the source set (if no source element was selected).

If the srcset attribute is present and has any image candidate strings using a width descriptor, the sizes attribute must also be present. If the srcset attribute is not specified, and the loading attribute is in the Lazy state, the sizes attribute may be specified with the value "auto" (ASCII case-insensitive). The sizes attribute is a sizes attribute, which contributes the source size to the source set (if no source element was selected).

An img element allows auto-sizes if:

• its loading attribute is in the Lazy state, and
• its sizes attribute's value is "auto" (ASCII case-insensitive), or starts with "auto," (ASCII case-insensitive).

Attributes/crossorigin

Support in all current engines.

Firefox8+Safari6+Chrome13+

The crossorigin attribute is a CORS settings attribute. Its purpose is to allow images from third-party sites that allow cross-origin access to be used with canvas.

The referrerpolicy attribute is a referrer policy attribute. Its purpose is to set the referrer policy used when fetching the image. [REFERRERPOLICY]

The decoding attribute indicates the preferred method to decode this image. The attribute, if present, must be an image decoding hint. This attribute's missing value default and invalid value default are both the auto state.

HTMLImageElement/fetchPriority

FirefoxNoSafari🔰 preview+Chrome102+

The fetchpriority attribute is a fetch priority attribute. Its purpose is to set the priority used when fetching the image.

The loading attribute is a lazy loading attribute. Its purpose is to indicate the policy for loading images that are outside the viewport.

When the loading attribute's state is changed to the Eager state, the user agent must run these steps:

1. Let resumptionSteps be the img element's lazy load resumption steps.

2. If resumptionSteps is null, then return.

3. Set the img's lazy load resumption steps to null.

4. Invoke resumptionSteps.

<img src="1.jpeg" alt="1">
<img src="2.jpeg" loading=eager alt="2">
<img src="3.jpeg" loading=lazy alt="3">
<div id=very-large></div> <!-- Everything after this div is below the viewport -->
<img src="4.jpeg" alt="4">
<img src="5.jpeg" loading=lazy alt="5">

In the example above, the images load as follows:

1.jpeg, 2.jpeg, 4.jpeg

The images load eagerly and delay the window's load event.

3.jpeg

The image loads when layout is known, due to being in the viewport, however it does not delay the window's load event.

5.jpeg

The image loads only once scrolled into the viewport, and does not delay the window's load event.

Developers are encouraged to specify a preferred aspect ratio via width and height attributes on lazy loaded images, even if CSS sets the image's width and height properties, to prevent the page layout from shifting around after the image loads.

The img HTML element insertion steps, given insertedNode, are:

1. If insertedNode's parent is a picture element, then, count this as a relevant mutation for insertedNode.

The img HTML element moving steps, given movedNode and oldParent, are:

1. If oldParent is a picture element, then, count this as a relevant mutation for movedNode.

The img HTML element removing steps, given removedNode and oldParent, are:

1. If oldParent is a picture element, then, count this as a relevant mutation for removedNode.

The img element must not be used as a layout tool. In particular, img elements should not be used to display transparent images, as such images rarely convey meaning and rarely add anything useful to the document.

What an img element represents depends on the src attribute and the alt attribute.

If the src attribute is set and the alt attribute is set to the empty string

The image is either decorative or supplemental to the rest of the content, redundant with some other information in the document.

If the image is available and the user agent is configured to display that image, then the element represents the element's image data.

Otherwise, the element represents nothing, and may be omitted completely from the rendering. User agents may provide the user with a notification that an image is present but has been omitted from the rendering.

If the src attribute is set and the alt attribute is set to a value that isn't empty

The image is a key part of the content; the alt attribute gives a textual equivalent or replacement for the image.

If the image is available and the user agent is configured to display that image, then the element represents the element's image data.

Otherwise, the element represents the text given by the alt attribute. User agents may provide the user with a notification that an image is present but has been omitted from the rendering.

If the src attribute is set and the alt attribute is not

The image might be a key part of the content, and there is no textual equivalent of the image available.

In a conforming document, the absence of the alt attribute indicates that the image is a key part of the content but that a textual replacement for the image was not available when the image was generated.

If the image is available and the user agent is configured to display that image, then the element represents the element's image data.

If the image has a src attribute whose value is the empty string, then the element represents nothing.

Otherwise, the user agent should display some sort of indicator that there is an image that is not being rendered, and may, if requested by the user, or if so configured, or when required to provide contextual information in response to navigation, provide caption information for the image, derived as follows:

1. If the image has a title attribute whose value is not the empty string, then return the value of that attribute.

2. If the image is a descendant of a figure element that has a child figcaption element, and, ignoring the figcaption element and its descendants, the figure element has no flow content descendants other than inter-element whitespace and the img element, then return the contents of the first such figcaption element.

3. Return nothing. (There is no caption information.)

If the src attribute is not set and either the alt attribute is set to the empty string or the alt attribute is not set at all

The element represents nothing.

Otherwise

The element represents the text given by the alt attribute.

The alt attribute does not represent advisory information. User agents must not present the contents of the alt attribute in the same way as content of the title attribute.

User agents may always provide the user with the option to display any image, or to prevent any image from being displayed. User agents may also apply heuristics to help the user make use of the image when the user is unable to see it, e.g. due to a visual disability or because they are using a text terminal with no graphics capabilities. Such heuristics could include, for instance, optical character recognition (OCR) of text found within the image.

While user agents are encouraged to repair cases of missing alt attributes, authors must not rely on such behavior. Requirements for providing text to act as an alternative for images are described in detail below.

The contents of img elements, if any, are ignored for the purposes of rendering.

The usemap attribute, if present, can indicate that the image has an associated image map.

The ismap attribute, when used on an element that is a descendant of an a element with an href attribute, indicates by its presence that the element provides access to a server-side image map. This affects how events are handled on the corresponding a element.

The ismap attribute is a boolean attribute. The attribute must not be specified on an element that does not have an ancestor a element with an href attribute.

The usemap and ismap attributes can result in confusing behavior when used together with source elements with the media attribute specified in a picture element.

The img element supports dimension attributes.

HTMLImageElement/alt

Support in all current engines.

Firefox1+Safari3+Chrome1+

HTMLImageElement/srcset

Support in all current engines.

Firefox38+Safari8+Chrome34+

HTMLImageElement/sizes

Support in all current engines.

Firefox38+Safari9.1+Chrome38+

The alt, src, srcset, and sizes IDL attributes must reflect the respective content attributes of the same name.

HTMLImageElement/crossOrigin

Support in all current engines.

Firefox8+Safari6+Chrome13+

The crossOrigin IDL attribute must reflect the crossorigin content attribute, limited to only known values.

HTMLImageElement/useMap

Support in all current engines.

Firefox1+Safari3+Chrome1+

The useMap IDL attribute must reflect the usemap content attribute.

HTMLImageElement/isMap

Support in all current engines.

Firefox1+Safari3+Chrome1+

The isMap IDL attribute must reflect the ismap content attribute.

HTMLImageElement/referrerPolicy

Support in all current engines.

Firefox50+Safari14+Chrome52+

The referrerPolicy IDL attribute must reflect the referrerpolicy content attribute, limited to only known values.

HTMLImageElement/decoding

Support in all current engines.

Firefox63+Safari11.1+Chrome65+

SVGImageElement/decoding

Firefox63+SafariNoChrome65+

The decoding IDL attribute must reflect the decoding content attribute, limited to only known values.

HTMLImageElement/loading

Support in all current engines.

Firefox75+Safari15.4+Chrome77+

The loading IDL attribute must reflect the loading content attribute, limited to only known values.

The fetchPriority IDL attribute must reflect the fetchpriority content attribute, limited to only known values.

image.width [ = value ]

HTMLImageElement/width

Support in all current engines.

Firefox1+Safari3+Chrome1+

Opera12.1+Edge79+ Edge (Legacy)12+Internet Explorer5.5+ Firefox Android?Safari iOS1+Chrome Android?WebView Android?Samsung Internet?Opera Android12.1+

image.height [ = value ]

HTMLImageElement/height

Support in all current engines.

Firefox1+Safari3+Chrome1+

Opera12.1+Edge79+ Edge (Legacy)12+Internet Explorer5.5+ Firefox Android?Safari iOS1+Chrome Android?WebView Android?Samsung Internet?Opera Android12.1+

These attributes return the actual rendered dimensions of the image, or 0 if the dimensions are not known.

They can be set, to change the corresponding content attributes.

image.naturalWidth

HTMLImageElement/naturalWidth

Support in all current engines.

Firefox1+Safari3+Chrome1+

Opera12.1+Edge79+ Edge (Legacy)12+Internet Explorer9+ Firefox Android?Safari iOS1+Chrome Android?WebView Android?Samsung Internet?Opera Android12.1+

image.naturalHeight

HTMLImageElement/naturalHeight

Support in all current engines.

Firefox1+Safari3+Chrome1+

Opera12.1+Edge79+ Edge (Legacy)12+Internet Explorer9+ Firefox Android?Safari iOS1+Chrome Android?WebView Android?Samsung Internet?Opera Android12.1+

These attributes return the natural dimensions of the image, or 0 if the dimensions are not known.

image.complete

HTMLImageElement/complete

Support in all current engines.

Firefox1+Safari3+Chrome1+

Opera12.1+Edge79+ Edge (Legacy)12+Internet Explorer5.5+ Firefox Android?Safari iOS1+Chrome Android?WebView Android?Samsung Internet?Opera Android12.1+

Returns true if the image has been completely downloaded or if no image is specified; otherwise, returns false.

image.currentSrc

HTMLImageElement/currentSrc

Support in all current engines.

Firefox38+Safari9.1+Chrome38+

Opera?Edge79+ Edge (Legacy)13+Internet ExplorerNo Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

Returns the image's absolute URL.

image.decode()

HTMLImageElement/decode

Support in all current engines.

Firefox68+Safari11.1+Chrome64+

Opera?Edge79+ Edge (Legacy)?Internet ExplorerNo Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

SVGImageElement/decode

Firefox68+SafariNoChrome64+

Opera?Edge79+ Edge (Legacy)?Internet ExplorerNo Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

This method causes the user agent to decode the image in parallel, returning a promise that fulfills when decoding is complete.

The promise will be rejected with an "EncodingError" DOMException if the image cannot be decoded.

image = new Image([ width [, height ] ])

HTMLImageElement/Image

Support in all current engines.

Firefox1+Safari1+Chrome1+

Opera8+Edge79+ Edge (Legacy)12+Internet Explorer5.5+ Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android10.1+

Returns a new img element, with the width and height attributes set to the values passed in the relevant arguments, if applicable.

The IDL attributes width and height must return the rendered width and height of the image, in CSS pixels, if the image is being rendered; or else the density-corrected natural width and height of the image, in CSS pixels, if the image has density-corrected natural width and height and is available but is not being rendered; or else 0, if the image is not available or does not have density-corrected natural width and height. [CSS]

On setting, they must act as if they reflected the respective content attributes of the same name.

The IDL attributes naturalWidth and naturalHeight must return the density-corrected natural width and height of the image, in CSS pixels, if the image has density-corrected natural width and height and is available, or else 0. [CSS]

Since the density-corrected natural width and height of an image take into account any orientation specified in its metadata, naturalWidth and naturalHeight reflect the dimensions after applying any rotation needed to correctly orient the image, regardless of the value of the 'image-orientation' property.

The complete getter steps are:

1. If any of the following are true:

   • both the src attribute and the srcset attribute are omitted;

   • the srcset attribute is omitted and the src attribute's value is the empty string;

   • the img element's current request's state is completely available and its pending request is null; or

   • the img element's current request's state is broken and its pending request is null,

   then return true.

2. Return false.

The currentSrc IDL attribute must return the img element's current request's current URL.

The decode() method, when invoked, must perform the following steps:

1. Let promise be a new promise.

2. Queue a microtask to perform the following steps:

   This is done because updating the image data takes place in a microtask as well. Thus, to make code such as

   img.src = "stars.jpg";
   img.decode();

   properly decode stars.jpg, we need to delay any processing by one microtask.

   1. Let global be this's relevant global object.

   2. If any of the following are true:

      • this's node document is not fully active; or

      • this's current request's state is broken,

      then reject promise with an "EncodingError" DOMException.

   3. Otherwise, in parallel, wait for one of the following cases to occur, and perform the corresponding actions:

      This img element's node document stops being fully active

      This img element's current request changes or is mutated

      This img element's current request's state becomes broken

      Queue a global task on the DOM manipulation task source with global to reject promise with an "EncodingError" DOMException.

      This img element's current request's state becomes completely available

      Decode the image.

      If decoding does not need to be performed for this image (for example because it is a vector graphic) or the decoding process completes successfully, then queue a global task on the DOM manipulation task source with global to resolve promise with undefined.

      If decoding fails (for example due to invalid image data), then queue a global task on the DOM manipulation task source with global to reject promise with an "EncodingError" DOMException.

      User agents should ensure that the decoded media data stays readily available until at least the end of the next successful update the rendering step in the event loop. This is an important part of the API contract, and should not be broken if at all possible. (Typically, this would only be violated in low-memory situations that require evicting decoded image data, or when the image is too large to keep in decoded form for this period of time.)

      Animated images will become completely available only after all their frames are loaded. Thus, even though an implementation could decode the first frame before that point, the above steps will not do so, instead waiting until all frames are available.

3. Return promise.

Without the decode() method, the process of loading an img element and then displaying it might look like the following:

const img = new Image();
img.src = "nebula.jpg";
img.onload = () => {
    document.body.appendChild(img);
};
img.onerror = () => {
    document.body.appendChild(new Text("Could not load the nebula :("));
};

However, this can cause notable dropped frames, as the paint that occurs after inserting the image into the DOM causes a synchronous decode on the main thread.

This can instead be rewritten using the decode() method:

const img = new Image();
img.src = "nebula.jpg";
img.decode().then(() => {
    document.body.appendChild(img);
}).catch(() => {
    document.body.appendChild(new Text("Could not load the nebula :("));
});

This latter form avoids the dropped frames of the original, by allowing the user agent to decode the image in parallel, and only inserting it into the DOM (and thus causing it to be painted) once the decoding process is complete.

Because the decode() method attempts to ensure that the decoded image data is available for at least one frame, it can be combined with the requestAnimationFrame() API. This means it can be used with coding styles or frameworks that ensure that all DOM modifications are batched together as animation frame callbacks:

const container = document.querySelector("#container");

const { containerWidth, containerHeight } = computeDesiredSize();
requestAnimationFrame(() => {
 container.style.width = containerWidth;
 container.style.height = containerHeight;
});

// ...

const img = new Image();
img.src = "supernova.jpg";
img.decode().then(() => {
    requestAnimationFrame(() => container.appendChild(img));
});

A legacy factory function is provided for creating HTMLImageElement objects (in addition to the factory methods from DOM such as createElement()): Image(width, height). When invoked, the legacy factory function must perform the following steps:

1. Let document be the current global object's associated Document.

2. Let img be the result of creating an element given document, "img", and the HTML namespace.

3. If width is given, then set an attribute value for img using "width" and width.

4. If height is given, then set an attribute value for img using "height" and height.

5. Return img.

A single image can have different appropriate alternative text depending on the context.

In each of the following cases, the same image is used, yet the alt text is different each time. The image is the coat of arms of the Carouge municipality in the canton Geneva in Switzerland.

Here it is used as a supplementary icon:

<p>I lived in <img src="carouge.svg" alt=""> Carouge.</p>

Here it is used as an icon representing the town:

<p>Home town: <img src="carouge.svg" alt="Carouge"></p>

Here it is used as part of a text on the town:

<p>Carouge has a coat of arms.</p>
<p><img src="carouge.svg" alt="The coat of arms depicts a lion, sitting in front of a tree."></p>
<p>It is used as decoration all over the town.</p>

Here it is used as a way to support a similar text where the description is given as well as, instead of as an alternative to, the image:

<p>Carouge has a coat of arms.</p>
<p><img src="carouge.svg" alt=""></p>
<p>The coat of arms depicts a lion, sitting in front of a tree.
It is used as decoration all over the town.</p>

Here it is used as part of a story:

<p>She picked up the folder and a piece of paper fell out.</p>
<p><img src="carouge.svg" alt="Shaped like a shield, the paper had a
red background, a green tree, and a yellow lion with its tongue
hanging out and whose tail was shaped like an S."></p>
<p>She stared at the folder. S! The answer she had been looking for all
this time was simply the letter S! How had she not seen that before? It all
came together now. The phone call where Hector had referred to a lion's tail,
the time Maria had stuck her tongue out...</p>

Here it is not known at the time of publication what the image will be, only that it will be a coat of arms of some kind, and thus no replacement text can be provided, and instead only a brief caption for the image is provided, in the title attribute:

<p>The last user to have uploaded a coat of arms uploaded this one:</p>
<p><img src="last-uploaded-coat-of-arms.cgi" title="User-uploaded coat of arms."></p>

Ideally, the author would find a way to provide real replacement text even in this case, e.g. by asking the previous user. Not providing replacement text makes the document more difficult to use for people who are unable to view images, e.g. blind users, or users or very low-bandwidth connections or who pay by the byte, or users who are forced to use a text-only web browser.

Here are some more examples showing the same picture used in different contexts, with different appropriate alternate texts each time.

<article>
 <h1>My cats</h1>
 <h2>Fluffy</h2>
 <p>Fluffy is my favorite.</p>
 <img src="fluffy.jpg" alt="She likes playing with a ball of yarn.">
 <p>She's just too cute.</p>
 <h2>Miles</h2>
 <p>My other cat, Miles just eats and sleeps.</p>
</article>

<article>
 <h1>Photography</h1>
 <h2>Shooting moving targets indoors</h2>
 <p>The trick here is to know how to anticipate; to know at what speed and
 what distance the subject will pass by.</p>
 <img src="fluffy.jpg" alt="A cat flying by, chasing a ball of yarn, can be
 photographed quite nicely using this technique.">
 <h2>Nature by night</h2>
 <p>To achieve this, you'll need either an extremely sensitive film, or
 immense flash lights.</p>
</article>

<article>
 <h1>About me</h1>
 <h2>My pets</h2>
 <p>I've got a cat named Fluffy and a dog named Miles.</p>
 <img src="fluffy.jpg" alt="Fluffy, my cat, tends to keep itself busy.">
 <p>My dog Miles and I like go on long walks together.</p>
 <h2>music</h2>
 <p>After our walks, having emptied my mind, I like listening to Bach.</p>
</article>

<article>
 <h1>Fluffy and the Yarn</h1>
 <p>Fluffy was a cat who liked to play with yarn. She also liked to jump.</p>
 <aside><img src="fluffy.jpg" alt="" title="Fluffy"></aside>
 <p>She would play in the morning, she would play in the evening.</p>
</article>

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.3