Question

我尝试用Promise Asynchronous调用我用NAN（Node.js的本地抽象）实现的本地C ++函数。不幸的是，承诺从未解决。我的Java代码。

function callbackDoAsyncStuffFirst() {
  return new Promise(function (resolve, reject) {
    module.doAsyncStuffFirst(function (error, a, v, b) {
      if (error) {
        return reject(error);
      }
      console.log("Resolve First: ", a, " ", b, " ", v, " ");
      let ret = [a, b, v];
      console.log("Return frist Resolve");
      return resolve(ret);
    });
  });
}

function callbackDoAsyncStuff() {
  return new Promise(function (resolve, reject) {
    module.doAsyncStuffSecond(function (error, a, b) {
      if (error) {
        return reject(error);
      }
      console.log("Returned: ", a, " ", b);
      let ret = [a, b];
      console.log("Call Second Resolve");
      return resolve(ret);
    }, 'valueA', 'valueB');
  });
}

let p = callbackDoAsyncStuffFirst().then((retArray) => { console.log("resolve first-->", retArray) });

let second = callbackDoAsyncStuff().then((retArray) => { console.log("resolve second-->: ", retArray) });

控制台输出看起来像

C++: Start Execute
C++: HandleOKCallback
JS: Resolve First:  a, b, v
JS: Return frist Resolve

此后，什么也没有发生。

Answer 1

这个伪造的模块表明问题出在您的C ++插件中，而不是您的JavaScript中，该问题在这里可以正常工作。

它还演示了如何使用一组“成功的”参数来调用回调，因为您将第一个回调参数解释为错误，该参数必须为false才能使您不拒绝诺言。

var module = {
  doAsyncStuffFirst: (cb) => {
    cb(undefined, 'dummy_a1', 'dummy_v1', 'dummy_b1');
  },
  doAsyncStuffSecond: (cb) => {
    cb(undefined, 'dummy_a2', 'dummy_b2');
  }
}

function callbackDoAsyncStuffFirst() {
  return new Promise(function (resolve, reject) {
    module.doAsyncStuffFirst(function (error, a, v, b) {
      if (error) {
        return reject(error);
      }
      console.log("Resolve First: ", a, " ", b, " ", v, " ");
      let ret = [a, b, v];
      console.log("Return frist Resolve");
      return resolve(ret);
    });
  });
}

function callbackDoAsyncStuff() {
  return new Promise(function (resolve, reject) {
    module.doAsyncStuffSecond(function (error, a, b) {
      if (error) {
        return reject(error);
      }
      console.log("Returned: ", a, " ", b);
      let ret = [a, b];
      console.log("Call Second Resolve");
      return resolve(ret);
    }, 'valueA', 'valueB');
  });
}

let p = callbackDoAsyncStuffFirst().then((retArray) => { console.log("resolve first-->", retArray) });

let second = callbackDoAsyncStuff().then((retArray) => { console.log("resolve second-->: ", retArray) });

解决Node.js承诺的最佳方法是什么？

1 个答案: