Question

嗨，我是这个迷人的“程序员”世界的新手。我开始构建一些简单的页面，这迫使我学习一些JS，我试图驯服节点，但它......对我来说很复杂。有人可以解释如何将代码的一部分传递到这个asyns世界的另一部分吗？我尝试过回调，我试过没有用，但也许我只是搞乱一些因为它对我来说是新的东西？

原始代码：

function ok(ifOk){
    console.log(ifOk);
}

function test(doSomeTests){
    console.log(doSomeTests);
}

let req1 = request1('http://www.facebook.com', function(err, resp, content){
    if (resp){
        if(content.indexOf('someUser') !== -1){
            var ifOk = 'ok';
            ok(ifOk);
            var doSomeTests = 'tests';
        }
    }
    else{
        console.log(err);
    }
});

let req2 = request2('http://www.google.com', function(err, resp, content){
    if (resp){
        // how to move do_some_tests here !?
        // I would like to start those 2 request immediately, so req1 is downloading data, req2 is downloading data,
        // and when req1 is finished and req2 is in the place it required the data to move forward - the data (doSomeTests) is passed in - is awailable to use
        test(do_some_test);
    }
    else{
        console.log(err);
    }
});

带回调的

代码：

// function after() {
    // setTimeout(function() {
        // console.log('after function - 3 sec setTimeout');
    // }, 3000);
// }

function test(doSomeTests) {
    console.log('doSomeTests is running: ' + doSomeTests);
}

function req1(_cb) {
    request('https://www.facebook.com', function (err, resp, content) {
        if (resp) {
            console.log('req1 in process...');

            if (resp.statusCode === 200) {
                var doSomeTests = 'tests';
                _cb(doSomeTests);
            }
        }
        if (content) {
            console.log('req1 is done!');
        }
        else {
          reject(err);
        }
    });
}

function req2() {
    request('https://www.google.com', function (err, resp, content) {
        if (resp) {
            console.log('req2 in process...');
            // how to move do_some_tests here !?
            // I would like to start those 2 requests immediately, so req1 is downloading data and also req2 is downloading data,
            // and when req1 is finished and req2 is in the place it required the data to move forward - the data (doSomeTests) is passed in - is awailable to use
            req1(test);
            // after();
        }
        if (content) {
            console.log('req2 is done!');
        }
        else {
            console.log(err);
        }
    });
}

req2();

带请求的

代码：

// function ok(ifOk) {
    // setTimeout(function() {
        // console.log(ifOk);
    // }, 2000);

// }

// function after(){
    // setTimeout(function(){
        // console.log('after function - 3 sec setTimeout');
    // }, 3000);
// }

function test(doSomeTests) {
  console.log('doSomeTests is running: ' + doSomeTests);
}

function req1() {
  return new Promise((resolve, reject) => {
    request('https://www.facebook.com', function (err, resp, content) {
      if (resp) {
            console.log('req1 in process...');

        if (resp.statusCode === 200) {
          // var ifOk = 'ok';
          // ok(ifOk);
          var doSomeTests = 'tests';
          resolve(doSomeTests);
        }

      }
        if (content) {
            console.log('req1 is done!');
        }
      else {
            reject(err);
      }
    })
  })
}

let req2 = req1().then(do_some_test => {
  request('https://www.google.com', function (err, resp, content) {
    if (resp) {
        console.log('req2 in process...');
      // I would like to start those 2 requests immediately, so req1 is downloading data, req2 is downloading data,
      // and when req1 is finished and req2 is in the place it required the data to move forward - the data (doSomeTests) is passed in - is awailable to use
      test(do_some_test);
        // after();
    }
    if (content) {
        console.log('req2 is done!');
    }
    else {
      console.log(err);
    }
  });
});

无论如何请求都不是异步下载内容。如何修改上面的代码以获得评论中的结果？

将数据从一个回调异步传递到另一个回调

0 个答案: