Short answer: paste TS or TSX, pick a target, read the JavaScript. A syntax error stops the compile and names the line; type errors are out of scope here.
Transpile, not type-check
This runs ts.transpileModule — the emitter behind every bundler’s TypeScript step. It is fast and it is faithful for syntax, but it never looks at other files, so it cannot know whether your types line up. That is why the page reports syntax diagnostics only, instead of showing a green tick that would mean nothing.
What the settings change
- Target — how far down to downlevel (optional chaining, classes, spreads).
- Module — ESNext keeps
import, CommonJS rewrites torequire. - JSX — treats the file as
.tsxand emits the automatic runtime by default.
Want to check a JSON payload instead? TheJSON Schema validator reports the exact failing path.