JS2Wasm

JS2Wasm compiles a subset of JavaScript to WebAssembly and runs directly in the browser. It focuses on performance and portability.

Installation

Currently a direct installation using npm or yarn is not possible. If you want to try the current version you have to clone the repository.

Usage

Run npm run build to compile and bundle the code. In order to compile a function you have to supply its code as a string and its function signatures as a map to the transpile function. The returned value is of the type CallWrapper.

const { Transpiler, WebAssemblyType } = js2wasm;
const wrapper = new Transpiler()
    .setSignature('add', WebAssemblyType.INT_32, WebAssemblyType.INT_32, WebAssemblyType.INT_32)
    .transpile('function add(a, b) { return a + b; }');
    
wrapper.setFunctionName('add').call(21, 21);

Benchmarks

To run the benchmarks you have to build them using npm run build then open the dist/benchmark/index.html in a browser.

The results are printed to the console in the following format:

jsMean, wasmMean, jsVariance, wasmVariance wasmCompilationMean, wasmImportMean, wasmExecutionMean, wasmExportMean

API

Transpiler

• new Transpiler(): void
  Creates a new transpiler with an empty hook class.
• new Transpiler(hooks: TranspilerHooks): void
  Creates a new transpiler with the specified hook instance.
• Transpiler#setSignature(name: string, returnType: WebAssemblyType, ...parameterTypes: WebAssemblyType[]): Transpiler
  Creates a mapping from the function name to the return type and the parameter types. The parameter types must be in the same order as they appear in the content string.
• Transpiler#transpile(content: string): CallWrapper
  Transpiles the specified content and checks the validity of the function signatures. The content can contain multiple functions.

WebAssemblyType

• INT_32
  The WebAssembly int32 type.
• FLOAT_64
  The WebAssembly float64 type.
• FLOAT_64_ARRAY
  An array of FLOAT_64 elements.
• INT_32_ARRAY
  An array of INT_32 elements.
• BOOLEAN
  The boolean type.

CallWrapper

• CallWrapper#setFunctionName(functionName: string): CallWrapper
  Set the name of the initial function to be called.
• CallWrapper#setOutParameters(...outParameters: any[]): CallWrapper
  Set the memory dependent parameters, of which the modified values need to be written back to JavaScript.
• CallWrapper#call(...parameters: any[]): any
  Calls the initial function of the transpiled Wasm code.

TranspilerHooks

TranspilerHooks is an interface. The following methods are hook methods, which get called by the Transpiler and the CallWrapper. The NullTranspilerHooks is the default implementation, in which all methods are empty.

• TranspilerHooks#beforeCompilation(): void
  Called before the transpilation process.
• TranspilerHooks#afterCompilation(): void
  Called after the transpilation process has finished.
• TranspilerHooks#beforeImport(): void
  Called before the memory import process.
• TranspilerHooks#afterImport(): void
  Called after the memroy import process has finished.
• TranspilerHooks#beforeExecution(): void
  Called before the Wasm code gets executed.
• TranspilerHooks#afterExecution(): void
  Called after the Wasm execution has finished.
• TranspilerHooks#beforeExport(): void
  Called before the memory export process.
• TranspilerHooks#afterExport(): void
  Called after the memory export process has finished.