lua-js-syntax

This is a transpiler from an alternative JS-inspired syntax for Lua to vanilla Lua.

Advantages:

• This is not a Lua VM fork, so you can use it with any VM implementation written in any language (like LuaJ for Java).
• Has syntax sugar that Lua is missing: continue, try-catch, throw, bitwise operators, compound operators, increments, decrements, arrow functions.
• You can use JS syntax highlighter to develop (given that you don't use Lua's OOP or # operator, which are invalid in normal JS)
• Converter can be run as a console app, optionally reading and writing to files.
• Line numbers are preserved during the conversion, so stacktraces will be accurate.

Disadvantages:

• To run the converter from non-JVM language, you need to run it as a console app.
• To run LuaJS code, you need to convert it to Lua first. No runtime support like in Moonscript.
• LuaJS is not a strict ECMAScript subset since it has Lua-like OOP, # and .. operators.

Alternative projects

• Moonscript: a language compiled to Lua, with completely new syntax. The project itself provides a transpiler and runtime support for any Lua VM.
• ljs: C Lua VM fork with JS-like syntax.
• jual: C Lua VM fork with JS-like syntax that is a ECMAScript subset.
• Killa: C Lua VM fork with JS-like syntax.

Comparison with Lua

LuaJS	Lua
/* A simple division function. */ let divide = (x, y) => { if (y == 0) { throw "Divisor is zero" } return x / y } try { print('Result is ' .. divide(10, 0)) } catch (e) { print('Error: ' .. e) }	--[[ A simple division function. ]]-- local divide = function(x, y) if (y == 0) then error("Divisor is zero") end return x / y end local res, e = pcall(function() print('Result is ' .. tostring(divide(10, 0))) end) if not res then print('Error: ' .. tostring(e)) end

See COMPARISON.md for full comparison.

Building

To build, you need:

• git
• JDK 8 or higher
• Maven

This will put JAR file to target dir and install it into local Maven repository:

git clone https://github.com/saharNooby/lua-js-syntax.git
cd lua-js-syntax
mvn clean install

Running

After build, you can either add this converter as a Maven dependency and use it from JVM-based language (Java, Kotlin, Scala etc.), or run it from console.

Add as a dependency

Maven dependency:

<dependency>
    <groupId>me.saharnooby</groupId>
    <artifactId>lua-js-syntax</artifactId>
    <version>1.0-SNAPSHOT</version>
</dependency>

Alternatively, you can just add the shaded JAR as a dependency directly to your build system.

Then you can use method me.saharnooby.luajssyntax.LuaJSToLua.convert(java.lang.String) or me.saharnooby.luajssyntax.LuaJSToLua.convert(java.lang.String, java.lang.Appendable). JavaDoc is available.

Run from console

• cd into target
• Run java -jar lua-js-syntax-1.0-SNAPSHOT-shaded.jar [source file] [destination file]

If the source file was not specified, source code will be read from stdin.

If the destination file was not specified, resulting code will be written to stdout.

Any errors will result in non-zero exit code and stacktraces printed to stderr.

Testing

The project has a list of unit tests comparing LuaJS code behavior to the behavior of manually written equivalent Lua code.