Windows : JavaScript Runtime Hosting Sample

jsrt-example.cpp

// JavaScript Runtime Hosting Sample
// https://code.msdn.microsoft.com/windowsdesktop/JavaScript-Runtime-Hosting-d3a13880/
#include <windows.h>
#include <jsrt.h>
#include <vector>
#include <string>
#pragma comment(lib, "jsrt.lib")


static void ThrowException(const std::wstring& errorString)
{
    JsValueRef errorValue;
    JsValueRef errorObject;
    JsPointerToString(errorString.c_str(), errorString.length(), &errorValue);
    JsCreateError(errorValue, &errorObject);
    JsSetException(errorObject);
}


static JsValueRef CALLBACK Echo(
      JsValueRef callee
    , bool isConstructCall
    , JsValueRef *arguments
    , unsigned short argumentCount
    , void *callbackState
) {
    for (auto index = 1u; index < argumentCount; ++index) {
        if (index > 1) {
            wprintf(L" ");
        }

        JsValueRef stringValue;
        const auto r0 = JsConvertValueToString(arguments[index], &stringValue);
        if(r0 != JsNoError) {
            ThrowException(L"invalid argument");
            return JS_INVALID_REFERENCE;
        }

        const wchar_t *string;
        size_t length;
        const auto r1 = JsStringToPointer(stringValue, &string, &length);
        if(r1 != JsNoError) {
            ThrowException(L"invalid argument");
            return JS_INVALID_REFERENCE;
        }

        wprintf(L"%s", string);
    }
    wprintf(L"\n");
    return JS_INVALID_REFERENCE;
}


int main() {
    _wsetlocale(LC_ALL, L"");

    std::wstring script = LR"(
        host.echo('42');
        for(var i = 0; i < host.arguments.length; ++i) {
            host.echo('host.arguments[' + i + '] = ', host.arguments[i]);
        }
    )";

    const wchar_t* sourceUrl = L"http://localhost/";

    std::vector<std::wstring> jsArgs;
    jsArgs.push_back(L"main_to_js_arg0");
    jsArgs.push_back(L"main_to_js_arg1");

    JsRuntimeHandle runtime;
    JsCreateRuntime(JsRuntimeAttributeNone, JsRuntimeVersion11, nullptr, &runtime);

    JsContextRef context;
    JsCreateContext(runtime, nullptr, &context);
    JsSetCurrentContext(context);

    {
        JsValueRef globalObject;
        JsGetGlobalObject(&globalObject);

        JsValueRef hostObject;
        JsCreateObject(&hostObject);

        JsPropertyIdRef hostPropertyId;
        JsGetPropertyIdFromName(L"host", &hostPropertyId);
        JsSetProperty(globalObject, hostPropertyId, hostObject, true);

        {
            const wchar_t* callbackName = L"echo";
            JsNativeFunction callbackFunc = Echo;
            void* callbackArg = nullptr;

            JsPropertyIdRef propertyId;
            JsGetPropertyIdFromName(callbackName, &propertyId);

            JsValueRef function;
            JsCreateFunction(callbackFunc, callbackArg, &function);

            JsSetProperty(hostObject, propertyId, function, true);
        }

        JsValueRef arguments;
        JsCreateArray(jsArgs.size(), &arguments);

        for (auto index = 0u; index < jsArgs.size(); ++index) {
            const auto* a = jsArgs[index].c_str();

            JsValueRef argument;
            JsPointerToString(a, wcslen(a), &argument);

            JsValueRef indexValue;
            JsIntToNumber(index, &indexValue);

            JsSetIndexedProperty(arguments, indexValue, argument);
        }

        JsPropertyIdRef argumentsPropertyId;
        JsGetPropertyIdFromName(L"arguments", &argumentsPropertyId);
        JsSetProperty(hostObject, argumentsPropertyId, arguments, true);
        JsSetCurrentContext(JS_INVALID_REFERENCE);
    }

    JsSetCurrentContext(context);
    const JsErrorCode errorCode = JsRunScript(script.c_str(), 0, sourceUrl, nullptr);

    if(errorCode == JsErrorScriptException) {
        JsValueRef exception;
        JsGetAndClearException(&exception);

        JsPropertyIdRef messageId;
        JsGetPropertyIdFromName(L"message", &messageId);

        JsValueRef messageValue;
        JsGetProperty(exception, messageId, &messageValue);

        const wchar_t *message;
        size_t length;
        JsStringToPointer(messageValue, &message, &length);

        wprintf(L"exception: %s\n", message);
        exit(EXIT_FAILURE);
    }

    if(errorCode != JsNoError) {
        wprintf(L"failed to run script.\n");
        exit(EXIT_FAILURE);
    }

    JsSetCurrentContext(JS_INVALID_REFERENCE);
    JsDisposeRuntime(runtime);
}