![]() Gecko-based, such as Firefox, SeaMonkey, XeroBank, Camino, Fennec and K-Meleon.The HTML 4.01 specification refers to the data URI scheme, and data URIs have now been implemented in most browsers.Īs of March 2012, Data URIs are supported by the following web browsers: The IETF published the data URI specification in 1998 as Proposed Standard on the IETF Standards Track, and hasn't progressed it since. One example is the conversion of HTML tables to downloadable CSV using a Data URI like this: 'data:text/csv charset=UTF-8,' + encodeURIComponent(csv), where "csv" has been generated by Javascript. In browsers that fully support Data URIs for "navigation", Javascript generated content can be provided as file "download" to the user, simply by setting to a Data URI. The data URI scheme is defined in RFC 2397 of the Internet Engineering Task Force (IETF). Data URIs are sometimes called Uniform Resource Locators, although they do not actually locate anything remote. This technique allows normally separate elements such as images and style sheets to be fetched in a single HTTP request rather than multiple HTTP requests, which can be more efficient.ĭata URIs tends to be simpler than other inclusion methods, such as MIME with cid or mid URIs. The data URI scheme is a URI scheme (Uniform Resource Identifier scheme) that provides a way to include data in-line in web pages as if they were external resources. Note that base64 encoding adds around 10% to the image size after gzip compression and this additional cost should be weighed against the benefits of fewer requests.īackground images can be encoded using the data URI scheme: url('data:image/png base64, ) These can be included in CSS as base64 encoded strings in order to avoid an additional HTTP request background images and gradients) are often used to improve the look and feel of an application. ![]() ![]() Mobile Web Application Best Practices Mobile Web Application Best Practices Include Background Images Inline in CSS Style Sheets Parameter := attribute "=" value SVN to base64 Data URL Scheme Syntax dataurl := "data:" "," data The LITLEN (1024) limits the number of characters which can appear in a singleĪttribute value literal, the ATTSPLEN (2100) limits the sum of all lengths of all attribute value specifications which appear in a tag, and the TAGLEN (2100) limits the overall length of a tag. Note that some applications that use URLs may impose a length limit for example, URLs embedded within anchors in HTML have a length limit determined by the SGML declaration for HTML. ![]() The " data:" URL scheme is only useful for short values. As a shorthand, " text/plain" can be omitted but the charset parameter supplied. If is omitted, it defaults to text/plain charset=US-ASCII. Without " base64", the data (as a sequence of octets) is represented using ASCII encoding for octets inside the range of safe URL characters and using the standard %xx hex encoding of URLs for octets outside that range. The is an Internet media type specification (with optional parameters.) The appearance of " base64" means that the data is encoded as base64. This document defines a new URL scheme that would work like 'immediate addressing'. ![]() Some applications that use URLs also have a need to embed (small) media type data directly inline.
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