It is often difficult to perceive any noticeable effect when using decoding on static elements. In practice, async means that the next paint does not wait for the image to decode. This attribute provides a hint to the browser as to whether it should perform image decoding along with rendering the other DOM content in a single presentation step that looks more "correct" ( sync), or render and present the other DOM content first and then decode the image and present it later ( async). See CORS settings attributes for additional information. If the attribute has an invalid value, browsers handle it as if the anonymous value was used. If the server does not opt into sharing credentials with the origin site (by sending back the Access-Control-Allow-Credentials: true response header), then the browser marks the image as tainted and restricts access to its image data. The CORS request is sent with any credentials included (that is, cookies, X.509 certificates, and the Authorization request header). If the crossorigin attribute is specified, then a CORS request is sent (with the Origin request header) but if the server does not opt into allowing cross-origin access to the image data by the origin site (by not sending any Access-Control-Allow-Origin response header, or by not including the site's origin in any Access-Control-Allow-Origin response header it does send), then the browser blocks the image from loading, and logs a CORS error to the devtools console.Ī CORS request is sent with credentials omitted (that is, no cookies, X.509 certificates, or Authorization request header). If the crossorigin attribute is not specified, then a non-CORS request is sent (without the Origin request header), and the browser marks the image as tainted and restricts access to its image data, preventing its usage in elements. Image data from a CORS-enabled image returned from a CORS request can be reused in the element without being marked " tainted". Indicates if the fetching of the image must be done using a CORS request. This attribute is also used when copying and pasting the image to text, or saving a linked image to a bookmark. Visual browsers will also hide the broken image icon if the alt attribute is empty and the image failed to display. Setting this attribute to an empty string ( alt="") indicates that this image is not a key part of the content (it's decoration or a tracking pixel), and that non-visual browsers may omit it from rendering. For these reasons and others, provide a useful value for alt whenever possible. In these cases, the browser may replace the image with the text in the element's alt attribute.
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