Question

我是V8的新手，并试图在我的C ++和JS代码之间创建一些绑定。问题是我无法跨不同的Javascript函数访问全局Javascript变量。原因是因为每个Javascript函数都被称为我不同的C ++函数。我想我的代码的问题是我在每个C ++函数中创建一个新的本地上下文。

我的JS代码：

var test = [];

function f1()
{
    var obj = {};
    obj.name = "Testing";
    test.push(obj);
}

function f2()
{
    var value = test[0].name;
}

我的C ++代码：

class Test 
{

  v8::Persistent<v8::Script> compiledScript;
  v8::Local<v8::Value> result;
  v8::Isolate* isolate;
  v8::Persistent<v8::Context> context;

  Test(filePath) {

      // Create and allocate isolate

      v8::Locker isolateLocker(isolate);
      v8::Isolate::Scope isolate_scope(isolate);
      v8::HandleScope handle_scope(isolate);
      // Create some bindings

      v8::Local<v8::Context> con = v8::Context::New(isolate, nullptr, binding_template);
      con->SetAlignedPointerInEmbedderData(0, &binder);

      context.Reset(isolate, con);
      v8::Context::Scope context_scope(con);

      std::string source_file = LoadFile(filePath);
      v8::Local<v8::String> sourceScript = v8::String::NewFromUtf8(isolate, source_file.c_str(), v8::NewStringType::kNormal).ToLocalChecked();
      v8::Local<v8::Script> script = v8::Script::Compile(con, sourceScript).ToLocalChecked();
      compiledScript.Reset(isolate, script);
}

void function1() 
{
    v8::Locker isolateLocker(isolate);
    v8::Isolate::Scope isolate_scope(isolate);               
    v8::HandleScope handle_scope(isolate);

    v8::Local<v8::Context> con= v8::Local<v8::Context>::New(isolate, context);
    v8::Local<v8::Script> script = v8::Local<v8::Script>::New(isolate, compiledScript);

    v8::Context::Scope context_scope(con);

    // Code to call the Javascript function f1

    result = script->Run(con).ToLocalChecked();
    v8::Local<v8::Object> global = con->Global();
    v8::Local<v8::Value> function_value1 = global->Get(v8::String::NewFromUtf8(isolate, "f1"));
    v8::Local<v8::Function> function1 = v8::Local<v8::Function>::Cast(function_value1);

    v8::Local<v8::Value> js_result1;

    js_result1 = function1->Call(con, global, 0, nullptr).ToLocalChecked();
}

void function2()
{
    v8::Locker isolateLocker(isolate);
    v8::Isolate::Scope isolate_scope(isolate);
    v8::HandleScope handle_scope(isolate);

    v8::Local<v8::Context> con = v8::Local<v8::Context>::New(isolate, context);
    v8::Local<v8::Script> script = v8::Local<v8::Script>::New(isolate, compiledScript);

    v8::Context::Scope context_scope(con);

    // Code to call the Javascript function f2

    result = script->Run(con).ToLocalChecked();
    v8::Local<v8::Object> global = con->Global();
    v8::Local<v8::Value> function_value2 = global->Get(v8::String::NewFromUtf8(isolate, "f2"));
    v8::Local<v8::Function> function2 = v8::Local<v8::Function>::Cast(function_value2);

    v8::Local<v8::Value> js_result2;

    js_result2 = function2->Call(con, global, 0, nullptr).ToLocalChecked();

 }
};
void main(int argcs, char* argvs[])
{
    V8::InitializeICUDefaultLocation(argvs[0]);
    V8::InitializeExternalStartupData(argvs[0]);
    Platform* platform = platform::CreateDefaultPlatform();
    V8::InitializePlatform(platform);
    V8::Initialize();

    Test test(jsFile);
    test.function1();
    test.function2();
}

执行上述JS代码时，出现错误，指出 name 是未定义的属性。我的理解是，在第二个函数中无法识别变量 test ，因为每个函数都在不同的上下文中执行。如果是这样，我如何让它们在相同的上下文中执行？如果没有，有人可以帮我理解并解决问题吗？

任何帮助将不胜感激：）

Answer 1

我想通了自己。错误是我每次都在所有功能中运行脚本。相反，我应该在构造函数中运行一次，就像编译一样。

如何在v8 Javascript中跨多个函数使用相同的上下文？

1 个答案: