Execute Lua scripts in the browser using Fengari WebAssembly with an interactive REPL console.
Paste a Lua chunk into the editor to execute it with the page's browser-resident Fengari environment, then inspect printed text and errors in the interactive console. It is suited to quick checks of Lua expressions, loops, tables, functions, and supported standard-library behavior without installing a desktop interpreter. The usual surprise is the host boundary: valid Lua can still fail when it expects arbitrary filesystem access, native C modules, or globals supplied by a game engine. Assignments do not print themselves in a normal script, so call print when output matters.
A concrete input and expected output from the current implementation.
Input
print(1 + 2 + 3 + 4)
print(string.reverse("Lua")) Expected output
10 auL
The first expression adds four integers and equals 10. Lua's string.reverse reverses the three ASCII characters in "Lua", producing "auL".
Running the editor sends its contents for evaluation as one Lua chunk. Statements execute in program order, and print writes its arguments to the console. A syntax error prevents the chunk from starting. An unhandled runtime error stops execution at the failing operation, so later statements in that chunk are not reached. The reported diagnostic is distinct from text deliberately printed by the script.
The Lua evaluator runs inside the browser rather than inside a desktop interpreter or game engine. Source and console activity remain on the device instead of being uploaded for execution. Pure Lua calculations can be tested directly, but files, native extensions, engine globals, and other host services exist only when the playground explicitly provides equivalents. Treat refreshing or closing the page as ending the current working session.
No. It shows that the tested chunk and execution path work in this playground's Fengari environment. A standalone interpreter may provide different libraries, while an embedded runtime may add or remove modules, globals, and host services. Test again in the real target when the script depends on files, networking, native extensions, version-specific behavior, or application callbacks.
Only when every referenced module and global is available in the playground. require cannot make an arbitrary local package, native module, or engine API appear in a browser runtime. Code that depends on objects supplied by a game engine is not self-contained Lua. Extract its pure calculation or data transformation, provide small test values, and run that isolated portion here.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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Write Markdown and see the rendered HTML output in real time with live preview.
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