1 Introduction

This document describes the level of support provided by Microsoft web browsers for the WebIDL Level 1 specification [W3C-WEBIDL1], published 15 December 2016. The [W3C-WEBIDL1] specification defines an interface definition language, Web IDL, that can be used to describe interfaces that are intended to be implemented in web browsers. Web IDL is an IDL variant with a number of features that allow the behavior of common script objects in the web platform to be specified more readily.