Web IDL is an

interface description language interface description language or interface definition language (IDL), is a generic term for a language that lets a program or object written in one language communicate with another program written in an unknown language. IDLs describe an inter ...

(IDL) format for describing

application programming interface An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how t ...

s (APIs) that are intended to be implemented in web browsers. Its adoption was motivated by the desire to improve the interoperability of web programming interfaces by specifying how languages such as ECMAScript should bind these interfaces.

Description

Web IDL is an IDL variant with: * A number of features that allow one to more easily describe the behavior of common script objects in a web context. * A mapping of how interfaces described with Web IDL correspond to language constructs within an

ECMAScript ECMAScript (; ES) is a JavaScript standard intended to ensure the interoperability of web pages across different browsers. It is standardized by Ecma International in the documenECMA-262 ECMAScript is commonly used for client-side scripting o ...

execution environment. Web specifications had been specified using OMG IDL since 1998, first with the DOM Level 1 specification. However, interfaces defined using OMG IDL were not able to specify behavior for JavaScript precisely, leading to issues with interoperability. WebIDL improved on this status quo by providing data types and binding specifications that make the intended behavior in JavaScript clearer.

Status of Web IDL specifications

The first edition of the Web IDL specification
became a Candidate Recommendation on 19 April 2012 and a

W3C Recommendation The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Founded in 1994 and led by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working to ...

on 15 December 2016. For many years th
Editor's Draft of a potential second edition
was what most new web specifications referenced. On 5 October 2021, the Editor's Draft was moved to th
WHATWG
as th
Web IDL Living Standard
per an

Usage

* The W3C Wiki has a list of W3C Specifications that use Web IDL, and nearly all

WHATWG The Web Hypertext Application Technology Working Group (WHATWG) is a community of people interested in evolving HTML and related technologies. The WHATWG was founded by individuals from Apple Inc., the Mozilla Foundation and Opera Software, lea ...

specifications use it. * The

Chromium Project Chromium is a free and open-source web browser project, mainly developed and maintained by Google. This codebase provides the vast majority of code for the Google Chrome browser, which is proprietary software and has some additional feature ...

has a page about using WebIDL to specify interfaces in

Blink Blinking is a bodily function; it is a semi-autonomic rapid closing of the eyelid. A single blink is determined by the forceful closing of the eyelid or inactivation of the levator palpebrae superioris and the activation of the palpebral portio ...

. * Mozilla uses Web IDL in their software creation process, mapping implementations to Web IDL specs. * When

WebKit WebKit is a browser engine developed by Apple and primarily used in its Safari web browser, as well as on the iOS and iPadOS version of any web browser. WebKit is also used by the BlackBerry Browser, PlayStation consoles beginning from the PS ...

is built, the IDL files are parsed, creates the code to bind interfaces to implementations. * In the

ES operating system This is a list of operating systems. Computer operating systems can be categorized by technology, ownership, licensing, working state, usage, and by many other characteristics. In practice, many of these groupings may overlap. Criteria for inclusio ...

, every system API is defined in Web IDL, and can be invoked from JavaScript directly.

References

External links

List of standards that use Web IDL

Web IDL syntax checker
{{Web interfaces Specification languages Web browsers