The **is‑es2015** package provides a tiny runtime check—`/^class\b/.test(class{})`—that tells you whether the current JavaScript environment supports native ES2015 features (e.g., class syntax). It’s aimed at developers who need to detect if their code is running on modern browsers/Node versus older environments (like IE11) to decide whether to use ES2015 constructs or fall back to pre‑ES2015 alternatives.