# Deno v0.20.0 — Release & Upgrade Intelligence
- **Product:** Deno (https://deno.com)
- **Version:** v0.20.0
- **Released:** Oct 07, 2019
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/deno/updates/v0.20.0/

## Executive Summary (TL;DR)
Deno v0.20.0. Source highlight: feat: Add Deno.hostname() (#3032)

## New Features
- feat: Add Deno.hostname() (#3032)
- feat: Add support for passing a key to Deno.env() (#2952)
- feat: JSX Support (#3038)
- feat: window.onunload (#3023)
- feat: test runner v2 (denoland/deno_std#604)
- feat: wss support with dialTLS (denoland/deno_std#615)

## Bug Fixes
- feat: Replace Isolate::set_dispatch with Isolate::register_op (#3002, #3039,
- fix: Async compiler processing (#3043)
- fix: Implement ignoreBOM option of UTF8Decoder in text_encoding (#3040)
- fix: Support top-level-await in TypeScript (#3024)
- fix: iterators on UrlSearchParams (#3044)
- fix: listenDefaults/dialDefaults may be overriden in some cases (#3027)