This document describes the artifact package accompanying the ASE’21 paper “JSTAR: JavaScript Specification Type Analyzer using Refinement.” The artifact includes JSTAR source code, the accepted paper, a companion report, ECMAScript (JavaScript specification) open-source repository as a git submodule, and scripts to replicate the data presented in the paper. JSTAR performs type analysis on any commit version of ECMAScript to detect type-related specification bugs. JSTAR is an extended tool of JISET, a JavaScript IR-based Semantics Extraction Toolchain. We hope that the artifact will be useful for contributors who update JavaScript specifications by automatically detecting type-related specification bugs before releasing them.