setTimeout的问题，试图等待异步执行 [英] setTimeout issue trying to wait for execution of async

问题描述

我是新来这种问题在javascript中，我无法修复这种企图等待异步调用结合角承诺的对象和超时。

功能onTimeout似乎从来执行。

  getAsyncContent：功能（asyncContentInfos）{    变种deferObj = $ q.defer（）;
    VAR promiseObj = deferObj.promise;
    asyncContentInfos.promiseObject = promiseObj;
    VAR blockingGuard = {做：假};    promiseObj.then（函数（）{
        blockingGuard.done = TRUE;
    }）;    this.wait =功能（）{
        VAR执行= FALSE;
        VAR onTimeout =功能（）{
            的console.log（************超时达到************）;
            执行= FALSE;
        };        而（！blockingGuard.done）{
            如果（执行和放大器;！＆安培;！blockingGuard.done）{
                执行= TRUE;
                的setTimeout（onTimeout，200）;
            }
        }
    };    $ http.get（asyncContentInfos.URL，{缓存：真}）
        。然后（功能（响应）{
            asyncContentInfos.responseData = response.data;
            的console.log（（getAsyncContent）asyncContentInfos.responseData（赛格瑞对象））;
            的console.log（asyncContentInfos.responseData）;
            deferObj.resolve（'（getAsyncContent）解析）;
            blockingGuard.done = TRUE;
            返回/*deferObj.promise*/ /*response.data*/;
        }，功能（errResponse）{
            VAR ERR_MSG ='（getAsyncContent）错误 - '+ errResponse;
            deferObj.reject（ERR_MSG）;
            console.error（ERR_MSG）;
        }）;    返回{
        等待：this.wait
    }
}
 

客户端code是这样的：

  VAR asyncVocabulary =新AsyncContentInfos（BASE_URL +'taxonomy_vocabulary.json'）;
getAsyncContent（asyncVocabulary）.wait（）;
 

和AsyncContentInfos是：

 函数AsyncContentInfos（URL）{
    this.URL =网址;
    this.responseData = [];
    this.promiseObject;
    }
 

解决方案

$ http.get 返回调用完成时，这将解决一个承诺。承诺是一种方法，使asyncronous更清洁，直比普通的旧回调衬里。

  getAsyncContent：功能（asyncContentInfos）{    返回$ http.get（asyncContentInfos.URL，{缓存：真}）
        。然后（功能（响应）{
            返回response.data;
        }，功能（errResponse）{
            console.error（ERR_MSG）;
            扔errResponse;
        }）;
}
 

然后使用它：

  getAsyncContent（{...}），然后（功能（yourDataIsHere）{}）;
 

有关承诺的好处是，他们可以很容易地链接起来。

  getAsyncContent（{...}）
  。然后（功能（yourDataIsHere）{
     返回anotherAsyncCall（yourDataIsHere）;
  }）
  。然后（功能（your2ndDataIsHere）{
  }）;
 

I'm new to this kind of problem in javascript and i can't fix this attempt to wait for an asynchronous call combining Angular promise objects and timeouts.

The function onTimeout seems never execute.

getAsyncContent: function (asyncContentInfos) {

    var deferObj = $q.defer();
    var promiseObj = deferObj.promise;
    asyncContentInfos.promiseObject = promiseObj;
    var blockingGuard = { done: false };

    promiseObj.then(function () {
        blockingGuard.done = true;
    });

    this.wait = function () {
        var executing = false;
        var onTimeout = function () {
            console.log("******************** timeout reached ********************");
            executing = false;
        };

        while (!blockingGuard.done) {
            if (!executing && !blockingGuard.done) {
                executing = true;
                setTimeout(onTimeout, 200);
            }
        } 
    };

    $http.get(asyncContentInfos.URL, { cache: true })
        .then(function (response) {
            asyncContentInfos.responseData = response.data;
            console.log("(getAsyncContent) asyncContentInfos.responseData (segue object)");
            console.log(asyncContentInfos.responseData);
            deferObj.resolve('(getAsyncContent) resolve');
            blockingGuard.done = true;
            return /*deferObj.promise*/ /*response.data*/;
        }, function (errResponse) {
            var err_msg = '(getAsyncContent) ERROR - ' + errResponse;
            deferObj.reject(err_msg);
            console.error(err_msg);
        });

    return {
        wait: this.wait
    }
}

Client code is something like this:

var asyncVocabulary = new AsyncContentInfos(BASE_URL + 'taxonomy_vocabulary.json');
getAsyncContent(asyncVocabulary).wait();

And AsyncContentInfos is:

function AsyncContentInfos(URL) {
    this.URL = URL;
    this.responseData = [];
    this.promiseObject;
    }

解决方案

$http.get returns a promise which will resolve when the call completes. Promises are a way to make asyncronous more clean and straight lined than plain old callbacks.

getAsyncContent: function (asyncContentInfos) {

    return $http.get(asyncContentInfos.URL, { cache: true })
        .then(function (response) {
            return response.data;
        }, function (errResponse) {
            console.error(err_msg);
            throw errResponse;
        });
}

Then using it:

getAsyncContent({...}).then(function(yourDataIsHere) {

});

The nice thing about promises is that they can be easily chained.

getAsyncContent({...})
  .then(function(yourDataIsHere) {
     return anotherAsyncCall(yourDataIsHere);
  })
  .then(function(your2ndDataIsHere) {
  });

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