Glue bindings for JavaScript using Embind

JavaScript (Wasm) bindings for Glue using Emscripten.

Usage

Example

Using EmGlue you can interact with JavaScript using a simple binding interface. The following example illustrates the basic usage.

#include <glue/emscripten/state.h>
#include <glue/class.h>
#include <iostream>

void exampleBasics() {
  glue::emscripten::State state;

  // run JS code
  state.run("console.log('Hello JavaScript!')");

  // extract values from JS
  std::cout << state.run("'Hello' + ' ' + 'C++!'")->get<std::string>() << std::endl;

  // extract maps
  auto map = state.run("({a: 1, b: '2'})").asMap();
  map["a"]->get<int>(); // -> 1

  // extract functions
  auto f = state.run("(a,b) => { return a+b }").asFunction();
  f(3, 4).get<int>(); // -> 7

  // inject values
  auto global = state.root();
  global["x"] = 42;
  global["square"] = [](double x){ return x*x; };
  
  // interact with JS directly
  state.run("console.log('square(x) =',square(x))");
  
  // or using Glue
  global["console"]["log"]("square(x) =", global["square"](global["x"]));
}

Classes and inheritance are also supported.

struct A {
  std::string member;
  A(std::string m): member(m) {}
  auto method() const { return "member: " + member; }
};

void exampleModules() {
  glue::emscripten::State state;

  // inject C++ classes and APIs into JavaScript
  auto module = glue::createAnyMap();
  
  module["A"] = glue::createClass<A>()
    .addConstructor<std::string>()
    .addMember("member", &A::member)
    .addMethod("method", &A::method)
  ;

  state.addModule(module, state.root());

  state.run("a = new A('test');");
  state.run("console.log('a.member() =',a.member());");
  state.run("console.log('a.method() =', a.method());");
  
  // there are no destructors in JavaScript 
  // -> be sure to delete your instances after use!
  state.run("a.delete(); a=undefined;");
}

Check the API and tests for functionality and examples. See here for a full example project using automatic TypeScript declarations.

Adding to your project

EmGlue can be easily integrated through CPM.cmake. If not available before, this will automatically add the Glue target as well.

CPMAddPackage(
  NAME EmGlue
  VERSION 0.2
  GITHUB_REPOSITORY TheLartians/EmGlue
)

target_link_libraries(myLibrary EmGlue)

Build and run tests

First, install and activate the emsdk. Then run the following commands from the project's root.

emcmake cmake -Htest -Bbuild
cmake --build build -j8
node build/EmGlueTests.js