@omni-wasm/cpp

C++ execution in the browser via JSCPP, a pure JavaScript C++ interpreter.

• Zero compilation — JSCPP interprets C++ code directly
• Pure JavaScript — No WASM build needed, works in any browser
• Lightweight — ~200 KB library
• Browser-native — No server, no API calls

Features

• iostream (cout, cerr, endl)
• Basic STL (string, vector, arrays)
• Classes, constructors, methods
• Loops (for, while, do-while)
• Conditionals (if/else, switch)
• Functions, recursion
• Pointers (basic support)
• Static members

Usage

import createRuntime from '@omni-wasm/cpp';

const runtime = await createRuntime();
const result = await runtime.execute(`
  #include <iostream>
  #include <string>
  using namespace std;
  
  int main() {
    cout << "Hello from C++" << endl;
    return 0;
  }
`);

console.log(result.stdout); // "Hello from C++\n"
runtime.destroy();

Browser Demo

Open examples/index.html in a browser to try C++ directly in your browser.

Limitations

JSCPP is an interpreter, not a compiler. Some advanced features are not supported:

• Templates (basic templates only)
• Complex STL containers (limited vector, map support)
• Inline assembly
• Custom memory allocation (no new/delete support)
• External C libraries

For production use cases requiring full C++ compliance, consider:

• @omni-wasm/wasm (Emscripten + LLVM) — full C++ but larger binary
• Server-side compilation — send C++ code to a backend compiler

API

Implements the standard WasmRuntime interface from @omni-wasm/shared:

interface ExecuteResult {
  stdout: string;
  stderr: string;
  exitCode: number;
  duration: number;
}

interface WasmRuntime {
  language: string;
  version: string;
  ready: boolean;
  execute(code: string, options?: ExecuteOptions): Promise<ExecuteResult>;
  reset(): Promise<void>;
  destroy(): void;
}

Options

interface ExecuteOptions {
  timeout?: number;    // Timeout in ms (default: 30000)
  stdin?: string;      // Input to pass to program
  args?: string[];     // Command-line arguments
}

interface RuntimeOptions {
  wasmUrl?: string;              // Custom JSCPP CDN URL
  onProgress?: (percent) => void; // Progress callback
}

Examples

Hello World

#include <iostream>
using namespace std;

int main() {
  cout << "Hello, World!" << endl;
  return 0;
}

Classes and Objects

#include <iostream>
using namespace std;

class Point {
  public:
    int x, y;
    Point(int px, int py) : x(px), y(py) {}
    void print() {
      cout << "(" << x << ", " << y << ")" << endl;
    }
};

int main() {
  Point p(10, 20);
  p.print();
  return 0;
}

Arrays and Loops

#include <iostream>
using namespace std;

int main() {
  int arr[] = {1, 2, 3, 4, 5};
  int sum = 0;
  for (int i = 0; i < 5; i++) {
    sum += arr[i];
  }
  cout << "Sum: " << sum << endl;
  return 0;
}

Technology Stack

• JSCPP 2.0.3 — JavaScript C++ interpreter
• Emscripten (for JSCPP compilation itself)
• TypeScript — Type-safe JavaScript

License

MIT — See LICENSE for details.