2 Basic Concepts

The remainder of this document is the formal specification of the TypeScript programming language and is intended to be read as an adjunct to the ECMAScript 2015 Language Specification (specifically, the ECMA-262 Standard, 6th Edition). This document describes the syntactic grammar added by TypeScript along with the compile-time processing and type checking performed by the TypeScript compiler, but it only minimally discusses the run-time behavior of programs since that is covered by the ECMAScript specification.