Google Closure Compiler vs TypeScript Playground

Google Closure Compiler optimizes JavaScript by analyzing code, removing dead code, and rewriting and minimizing what remains. It can also check syntax, references, and types, and warn about illegal JavaScript, risky operations, and common pitfalls. Google says smaller output files can help applications load faster and reduce bandwidth needs. Compilation options include WHITESPACE_ONLY, SIMPLE, and ADVANCED; the repository README also lists BUNDLE. ADVANCED applies aggressive transformations and symbol renaming to improve compression, so preserving program behavior requires care. The project is available as a command-line Java application, a library used through Bazel, and an NPM package. Released JARs are distributed through Maven. The repository documents Maven, NPM, Bazel, command-line Java, and a NodeJS API. Building the compiler requires Java 21 or later, NodeJS, Git, and Bazelisk. Its input restrictions include use of goog.module() and goog.require(), and ES6 import/export support is not actively maintained. The NPM packages are built and distributed by an open source contributor, not Google. The compiler is free.

TypeScript Playground is a free browser environment for writing, running, sharing, and safely experimenting with TypeScript and JavaScript. It accepts .ts, .tsx, .js, .jsx, and .d.ts files. Run converts code to JavaScript, executes it in the current browser session, and shows console output in Logs; the browser session can also support DOM API experiments. The editor centers on one text document and is described as a teaching tool that needs no setup. Users can select supported TypeScript builds, including beta, nightly, pull request, and older builds. The TS Config panel exposes a focused compiler-option set, while twoslash annotations can configure options beyond it. URLs can preserve code, compiler flags, and settings for sharing. Export can create Markdown, open TypeScript AST Viewer, or export a project to CodeSandbox or StackBlitz. Plugins are supported, including Presentation Mode, Clippy, TSQuery, Collaborate, and Transformer. The mobile layout uses a single pane and does not show transpiled JavaScript beside source.