从jQuery的嵌套函数的返回值 [英] return value from nested function in jquery

问题描述

我有一个code，它从嵌套函数返回值给出的问题。结果
检查这个code。

i have a code that give problem on returning value from nested function.
check this code.

function test(){
  var flag=true;
  $.post('path/of/file.php',{data:data},function(r){
     if(r == 1){ flag=false; }
  });
      return flag;
}

此功能测试总是返回真正。因为它没有回电 $的功能等待返回值。发布。如果我在回调函数中返回它是不行的。因此，如何从这个问题的解决。结果
谢谢...

this function test always return true. because it return value without waiting of call back function of $.post. if i return within the callback function it is not work. so, how can i overcome from this problem.
thanks...

推荐答案

由于运行.post的异步你的方法总是在瞬间返回true。但如何对返回推迟而不是反对呢？我知道这是不是你问了一个不同的方法，它可能并不适用于您的方案。

Since .post runs async your method will always return true at the moment. But how about returning a deferred object instead? I realize that this is a different approach than the one you're asking for, and it might not be applicable for your scenario.

这样的事情（从我的头顶）：

Something like this (from the top of my head):

function test(){
   var def = new $.Deferred();   
    $.ajax({
        url: 'test',
        success: function(data) {
            // Do some minor logic to determine if server response was success.
            console.log('success in callback');
            if(data == true){
              def.resolve(true);  
            }
            else{
              def.reject(); 
              // or possibly def.resolve(true) depending what you're looking for.
            }

        },
        error:function(){
          console.log('error in callback');
          def.reject();
        }
    });

  return def; 
}

function testMethod(){
  var defObject = test();
  defObject.done(function(result){
    console.log('done in deferred');
    // Do something when everything went well.

  }).fail(function(){
    console.log('error in deferred');
    // Do something when something went bad.
  });
}

$(document).ready(function(){
  testMethod();  
});

递延

可以很容易地听异步回调。这是当你想要做一些逻辑，一个至关重大要求完成一个共同的模式，而是要在逻辑与请求本身分开。

Deferred makes it easy to listen async callbacks. It's a common pattern when you want to do some logic efter a request is done, but you want to separate the logic from the request itself.

更多的例子在这里：
的http://blog.mediumequalsmessage.com/promise-deferred-objects-in-javascript-pt2-practical-use

一个plunkr例如：
http://plnkr.co/edit/LsNjfx4alNzshOQb2XAW?p=$p$pview

A plunkr example: http://plnkr.co/edit/LsNjfx4alNzshOQb2XAW?p=preview

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