Data URI scheme

The Fetch standard defines requests, responses, and the process that binds them: fetching. To do so it also supersedes the HTTP Origin header semantics originally defined in The Web Origin Concept. [[ORIGIN]]( "The Web Origin Concept") Numerous APIs provide the ability to fetch a resource, e.g. HTML’s img and script element, CSS' cursor and list-style-image , the navigator.sendBeacon() and self.importScripts() JavaScript APIs. The Fetch Standard provides a unified architecture for these features so they are all consistent when it comes to various aspects of fetching, such as redirects and the CORS protocol. The Fetch Standard also defines the fetch() JavaScript API, which exposes most of the networking functionality at a fairly low level of abstraction. This specification uses terminology from ABNF, Encoding, HTML, HTTP, MIME Sniffing, Streams, URL, Web IDL, WebSockets, and WebTransport. [[ABNF]]( "Augmented BNF for Syntax Specifications: ABNF") [[ENCODING]]( "Encoding Standard") [[HTML]]( "HTML Standard") [[HTTP]]( "HTTP Semantics") [[MIMESNIFF]]( "MIME Sniffing Standard") [[STREAMS]]( "Streams Standard") [[URL]]( "URL Standard") [[WEBIDL]]( "Web IDL Standard") [[WEBSOCKETS]]( "WebSockets Standard") [[WEBTRANSPORT]]( "WebTransport") A fetch timing info is a struct used to maintain timing information needed by Resource Timing and Navigation Timing. It has the following items : [[RESOURCE-TIMING]]( "Resource Timing") [[NAVIGATION-TIMING]]( "Navigation Timing") A response body info is a struct used to maintain information needed by Resource Timing and Navigation Timing. It has the following items : [[RESOURCE-TIMING]]( "Resource Timing") [[NAVIGATION-TIMING]]( "Navigation Timing") To create an opaque timing info, given a fetch timing info timingInfo, return a new fetch timing info whose start time and post-redirect start time are timingInfo’s start time . 2. Otherwise, queue a global task on the networking task source with taskDestination and algorithm. If the user agent assumes it does not have internet connectivity, then return true. HTTP(S) scheme and fetch scheme are also used by HTML. [[HTML]]( "HTML Standard") While fetching encompasses more than just HTTP, it borrows a number of concepts from HTTP and applies these to resources obtained via other means (e.g., data URLs). HTTP whitespace is only useful for specific constructs that are reused outside the context of HTTP headers (e.g., MIME types ). For HTTP header values, using HTTP tab or space is preferred, and outside that context ASCII whitespace is preferred. Unlike ASCII whitespace this excludes U+000C FF. 7. Return the code points from positionStart to position, inclusive, within input. A method is a byte sequence that matches the method token production. A forbidden method is a method that is a byte-case-insensitive match for CONNECT , TRACE , or TRACK . [[HTTPVERBSEC1]]( "Multiple vendors' web servers enable HTTP TRACE method by default.") , [[HTTPVERBSEC2]]( "Microsoft Internet Information Server (IIS) vulnerable to cross-site scripting via HTTP TRACK method.") , [[HTTPVERBSEC3]]( "HTTP proxy default configurations allow arbitrary TCP connections.") Normalization is done for backwards compatibility and consistency across APIs as methods are actually "case-sensitive". HTTP generally refers to a header as a "field" or "header field". The web platform uses the more colloquial term "header". [[HTTP]]( "HTTP Semantics") To get a structured field value given a header name name and a string type from a header list list, run these steps. They return null or a structured field value . 4. Let result be the result of parsing structured fields with input string set to value and header type set to type. Get a structured field value intentionally does not distinguish between a header not being present and its value failing to parse as a structured field value . This ensures uniform processing across the web platform. Structured field values are defined as o