Nodejs承诺不能正常工作？

我正在使用nodejs和库Promises / A +（选择它似乎是最受欢迎的库）https://www.npmjs.com/package/promise。我面临的问题是，即使异步功能已按预期完成，但在失败声明后仍已完成。因此sv + ' No it failed'，总是在async方法中的console.log消息（表明成功）之前打印此消息。此console.log消息应该先打印出来，因为它在async方法内部。我被困住为什么会这样？即使异步方法成功返回后，promise也总是在失败时运行？

我的代码：

 var promise = new Promise(function (resolve, reject) {

        var u = asyncmethod(some_var);

            if (u){
                resolve(some_var)
            }
            else{
                reject(some_var);
            }
    });


    promise.then(function(sv) {
        console.log(sv + ' Yes it worked');
    }, function(em) {
        console.log(sv + ' No it failed');
    });

Medet Tleuka.. 5

您的异步方法有问题，应该是异步功能

var promise = new Promise(function (resolve, reject) {
     //var u = asyncmethod(some_var); // <-- u is not defined, even if you return result stright, as it's the nature of async

     asyncmethod(some_var, function(err, result){ //pass callback to your fn
         if(err){
             reject(err);
         } else {
             resolve(result);
         }
     });
});
promise.then(function(successResponse) { //better name variables 
     console.log(successResponse + ' Yes it worked');
}, function(errorResponse) {
     console.log(errorResponse + ' No it failed');
});

//and simple implementation of async `asyncmethod`
var asyncmethod = function(input, callback){
    setTimeout(function(){
        callback(null, {new_object: true, value: input});
    }, 2000); //delay for 2seconds
}

注意：顾名思义，此答案认为asyncmethod是异步的

您的异步方法有问题，应该是异步功能

var promise = new Promise(function (resolve, reject) {
     //var u = asyncmethod(some_var); // <-- u is not defined, even if you return result stright, as it's the nature of async

     asyncmethod(some_var, function(err, result){ //pass callback to your fn
         if(err){
             reject(err);
         } else {
             resolve(result);
         }
     });
});
promise.then(function(successResponse) { //better name variables 
     console.log(successResponse + ' Yes it worked');
}, function(errorResponse) {
     console.log(errorResponse + ' No it failed');
});

//and simple implementation of async `asyncmethod`
var asyncmethod = function(input, callback){
    setTimeout(function(){
        callback(null, {new_object: true, value: input});
    }, 2000); //delay for 2seconds
}

注意：顾名思义，此答案认为asyncmethod是异步的