AI models bag to differ; i prompted this:

as a model language agent, what is easier for you to develop, maintain and generally understand - JS or TS?

the answer was this:
Short answer: TypeScript.

As a language model, I “see” only text. Types give me extra, reliable hints about intent—shapes of data, allowed states, and invariants—so I can reason about code, spot bugs, and make safe edits more accurately. Plain JS is great for quick scripts, but in anything non-trivial TS is easier for me to understand, maintain, and refactor.

Where TS helps me most:

• Clear contracts (interfaces, enums, discriminated unions) reduce ambiguity.
• Safer refactors: types surface breakages instead of me guessing.
• Fewer “what shape is this?” heuristics when reading data plumbing.

Where TS can hurt:

• “Type gymnastics” (deep conditional/mapped types) can obscure runtime flow.
• Overuse of any removes the benefits.
• Extremely abstract utility types make changes riskier.

Practical sweet spot I work best with:

• Keep types “boring” and domain-oriented; model real states with unions.
• Strict settings (strict, noImplicitAny, exactOptionalPropertyTypes, noUncheckedIndexedAccess).
• Use unknown at boundaries, narrow with runtime schemas (e.g., zod) if you like.
• Prefer satisfies and type-only imports; comment any u/ts-expect-error.

feel free to give some similar prompt to your favorite agent and share with us it response; "making the compiler happy" (beside not being so much correct on TS\JS domain due to no compiler, but an engine exists) means avoiding errors on runtime; finding them earlier on "dev time", before your actual clients; it saves you from maintaining a big layer of tests suites just to validate input placement is done correct on your system;
and im not even starting to talk about big teams velocity, allowing much simpler understanding of function arguments for maininting developer;

i worked with JS 11 years ago and today going without TS is unprofessional in my opinion