Web IDL is an interface description language (IDL) format for describing application programming interfaces (APIs) that are intended to be implemented in web browsers.
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 execution environment.
The first edition of the Web IDL specification became a Candidate Recommendation on 19 April 2012. The second edition of Web IDL is an Editor's Draft, and most new web specifications reference this second edition.
The W3C Wiki has a list of W3C Specifications that use Web IDL, and nearly all WHATWG specifications use it.
The Chromium Project has a page about using WebIDL to specify interfaces in Blink.
Mozilla uses Web IDL in their software creation process, mapping implementations to Web IDL specs.
When WebKit is built, the IDL files are parsed, creates the code to bind interfaces to implementations.
