<a>

Attributes

This element's attributes include the global MathML attributes as well as the following attributes:

download

Causes the browser to treat the linked URL as a download. Can be used with or without a filename value:

Without a value, the browser will suggest a filename/extension, generated from various sources:
- The Content-Disposition HTTP header
- The final segment in the URL path
- The media type (from the Content-Type header, the start of a data: URL, or Blob.type for a blob: URL)
filename: defining a value suggests it as the filename. / and \ characters are converted to underscores (_). Filesystems may forbid other characters in filenames, so browsers will adjust the suggested name if necessary. This adjustment happens when the download is triggered and is not observable via the MathMLAnchorElement.download property.

Note:

download only works for same-origin URLs, same-origin blob:, and data: schemes. For other URLs, the download attribute is ignored and a normal navigation happens, although the target page may still use Content-Disposition to instruct a download.
How browsers treat downloads varies by browser, user settings, and other factors. The user may be prompted before a download starts, or the file may be saved automatically, or it may open automatically, either in an external application or in the browser itself.
The download attribute, when honored, overrides the Content-Disposition: inline behavior, but the filename parameter of Content-Disposition overrides the name in the download attribute.

href

The URL that the hyperlink points to. Links are not restricted to HTTP-based URLs — they can use any URL scheme supported by browsers:

Telephone numbers with tel: URLs
Email addresses with mailto: URLs
SMS text messages with sms: URLs
Executable code with javascript: URLs
While web browsers may not support other URL schemes, websites can with registerProtocolHandler()

Moreover other URL features can locate specific parts of the resource, including:

Sections of a page with document fragments
Specific text portions with text fragments
Pieces of media files with media fragments

hreflang

Hints at the human language of the linked URL. No built-in functionality. Allowed values are the same as the global HTML lang attribute.

ping

A space-separated list of URLs. When the link is followed, the browser will send POST requests with the body PING to the URLs. Typically for tracking.

referrerpolicy

How much of the referrer to send when following the link, and under what circumstances.

no-referrer: The Referer header will not be sent.
no-referrer-when-downgrade: The Referer header will not be sent to origins without TLS (HTTPS).
origin: The sent referrer will be limited to the origin of the referring page: its scheme, host, and port.
origin-when-cross-origin: The referrer sent to other origins will be limited to the scheme, the host, and the port. Navigations on the same origin will still include the path.
same-origin: A referrer will be sent for same origin, but cross-origin requests will contain no referrer information.
strict-origin: Only send the origin of the document as the referrer when the protocol security level stays the same (HTTPS→HTTPS), but don't send it to a less secure destination (HTTPS→HTTP).
strict-origin-when-cross-origin (default): Send a full URL when performing a same-origin request, only send the origin when the protocol security level stays the same (HTTPS→HTTPS), and send no header to a less secure destination (HTTPS→HTTP).
unsafe-url: The referrer will include the origin and the path (but not the fragment, password, or username). This value is unsafe, because it leaks origins and paths from TLS-protected resources to insecure origins.

rel

The relationship of the linked URL as space-separated link types. See the rel HTML attribute page for more information.

target

Where to display the linked URL, as the name for a browsing context (a tab, window, or <iframe>). The following keywords have special meanings for where to load the URL:

_self: The current browsing context. (Default)
_blank: Usually a new tab, but users can configure browsers to open a new window instead.
_parent: The parent browsing context of the current one. If no parent, behaves as _self.
_top: The topmost browsing context. To be specific, this means the "highest" context that's an ancestor of the current one. If no ancestors, behaves as _self.

type

Hints at the linked URL's format with a MIME type. No built-in functionality.

Examples

Basic usage

This example marks up the Gamma function in MathML. It includes several MathML <a> elements to link individual parts of the formula to their respective sections on the Wiki page.

MathML

html

<math display="block" xmlns="http://www.w3.org/1998/Math/MathML"
  ><semantics
    ><mrow
      ><a href="https://en.wikipedia.org/wiki/Gamma_function"
        ><mrow
          ><mi mathvariant="normal">Γ</mi><mo stretchy="false">(</mo><mi>t</mi
          ><mo stretchy="false">)</mo></mrow
        ></a
      ><mo>=</mo
      ><a href="https://en.wikipedia.org/wiki/Gamma_function#Main_definition"
        ><mrow
          ><msubsup
            ><mo>∫</mo><mn>0</mn><mrow><mo>+</mo><mn>∞</mn></mrow></msubsup
          ><msup
            ><mi>x</mi><mrow><mi>t</mi><mo>−</mo><mn>1</mn></mrow></msup
          ><msup
            ><mi>e</mi><mrow><mo>−</mo><mi>x</mi></mrow></msup
          ><mi>d</mi><mi>x</mi></mrow
        ></a
      ><mo>=</mo
      ><a
        href="https://en.wikipedia.org/wiki/Gamma_function#Euler's_definition_as_an_infinite_product"
        ><mrow
          ><mfrac><mn>1</mn><mi>t</mi></mfrac
          ><munderover
            ><mo>∏</mo><mrow><mi>n</mi><mo>=</mo><mn>1</mn></mrow
            ><mn>∞</mn></munderover
          ><mfrac
            ><msup
              ><mrow
                ><mo>(</mo
                ><mrow
                  ><mn>1</mn><mo>+</mo><mfrac><mn>1</mn><mi>n</mi></mfrac></mrow
                ><mo>)</mo></mrow
              ><mi>t</mi></msup
            ><mrow
              ><mn>1</mn><mo>+</mo><mfrac><mi>t</mi><mi>n</mi></mfrac></mrow
            ></mfrac
          ></mrow
        ></a
      ><a href="https://en.wikipedia.org/wiki/Asymptotic_analysis#Definition"
        ><mo>∼</mo></a
      ><a href="https://en.wikipedia.org/wiki/Gamma_function#Stirling's_formula"
        ><mrow
          ><msqrt
            ><mfrac
              ><mrow><mn>2</mn><mi>π</mi></mrow
              ><mi>t</mi></mfrac
            ></msqrt
          ><msup
            ><mrow
              ><mo>(</mo><mfrac><mi>t</mi><mi>e</mi></mfrac
              ><mo>)</mo></mrow
            ><mi>t</mi></msup
          ></mrow
        ></a
      ></mrow
    ></semantics
  ></math
>