如何使用YAHOO.util.Connect.asyncRequest并返回结果？ [英] How to use YAHOO.util.Connect.asyncRequest and return results?

问题描述

我正在使用YAHOO.util.Connect.asyncRequest从数据库中获取数据，这里是代码：

I'm using YAHOO.util.Connect.asyncRequest to get data from database, here is the code :

function getCountArticle(contentCurValue) {

  var handleSuccess = function (res) {
      var countPubmed = YAHOO.lang.JSON.parse(res.responseText);
      var contentCountPubmed = countPubmed.totalArticleRecords;
      alert(contentCountPubmed); //return 15 for example
  };

  var handleFailure = function () {
      alert("Error connecting data : Bad pubmed query");
  };

  var callback =
  {
    success:handleSuccess,
    failure:handleFailure,
    timeout: 5000
  };

  var sURL = 'qct-list-article.html?term=' + contentCurValue + '&retstart=0' + '&retmax=1';

  var request = YAHOO.util.Connect.asyncRequest('GET',sURL,callback);

}

我希望此函数返回：contentCurValue（例如：15），但是当我尝试使用这段代码时，我得到未定义：

I would like this function return : "contentCurValue" (eg:15), but when I try to use this code I get "undefined" :

var test = getCountArticle();
alert(test); // return undefined, should return 15

我的错误可能是由于异步查询，但我怎么能强制var test = getCountArticle（）; 等待结果？

My error is probably due to asynchronous query, but how can I force "var test = getCountArticle();" to wait for results ?

推荐答案

由于调用本质上是异步的，而不是试图等待对于响应，最好指定一个回调函数来执行数据。您可以像这样修改您的方法：

Since the call is by nature asynchronous, rather than try to wait for the response, you would be better off specifying a callback function to execute with the data. You could modify your method like this:

 function getCountArticle(contentCurValue, callback) {
  var handleSuccess = function (res) {
      var countPubmed = YAHOO.lang.JSON.parse(res.responseText);
      var contentCountPubmed = countPubmed.totalArticleRecords;
      callback(contentCountPubmed); //return 15 for example
  };
  // ...
} 

然后你的主叫代码是：

then your calling code would be:

 getCountArticle("contentCurValue", function(test) {
    alert(test);
}); 

使用从AJAX查询返回的值的任何进一步执行都将在您的回调方法中进行。

Any further execution using the value returned from your AJAX query would proceed inside of your callback method.

这个SO帖子基本上是同一个问题，但不是YUI特定的：在调用ajax时在javascript中获取未定义

This SO post is essentially the same problem, but not YUI specific: Getting undefined in javascript when calling ajax

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