Comparisons
Checked JavaScript compared
Side-by-side comparisons for the decisions around checked JavaScript: whether to write .ts files instead, which config file to use, which TypeScript version, and what Node.js, Deno, Bun and Flow do differently.
Each comparison is dated and says what was verified and how. Code on these pages is checked with tsc like every other example on the site; claims about tools this site does not run are marked as coming from their documentation.
All comparisons
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JSDoc-typed JavaScript vs TypeScript files
The same checker reads both. What differs is syntax, the build step, and what each can express: a dated comparison with examples checked by tsc.
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JSDoc-typed JavaScript vs Node's type stripping
Node.js now runs .ts files by erasing their types. What that changes about the no-build-step argument, what it does not do, and which Node.js versions do it.
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jsconfig.json vs tsconfig.json
The same file format with different defaults: what a jsconfig.json turns on by itself, how tsc and editors find each file, and when to use which.
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TypeScript 5.9 vs 6.0 vs 7.0 for JavaScript projects
What changes for checked JavaScript across TypeScript 5.9, 6.0 and the 7.0 native port: defaults, removed options, JSDoc 7.0 drops, speed, and an upgrade path.
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JSDoc with TypeScript vs Flow
Two ways to type JavaScript in comments: TypeScript's checker reading JSDoc, and Flow's comment types. Where each stands today, and how to move from Flow.
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Checking JavaScript in Node.js, Deno and Bun
What each runtime checks before and while it runs your JavaScript, which config each reads, and the commands, with one sample file checked by tsc.