Javascript：功能中的函數並返回

Question

我在自定義函數中有ajax函數，我需要調用我的自定義函數並從ajax函數中獲取一些變量。爲什麼這是不可能的？

1想法：

<script> 
    function getValue(){ 

     $.nette.ajax({ 
      url: "http://example.com/request", 
      contentType: 'application/json', 
      dataType: 'json', 
      success: function(payload) { 
       console.log(payload.value); // contains RIGHT value 
       return payload.value; 
      } 
     }); 
    } 

    var try = getValue(); 
    console.log(try); // = undefined 
</script> 

第二個想法：

<script> 
    function getValue(){ 
     var returning = ""; 

     $.nette.ajax({ 
      url: "http://example.com/request", 
      contentType: 'application/json', 
      dataType: 'json', 
      success: function(payload) { 
       returning = payload.value; 
       console.log(payload.value); // contains RIGHT value 
      } 
     }); 
      console.log(returning); // = "" 
    } 

</script> 

Answer 1

AJAX是一種承諾。在請求成功時使用回調做某事

function getValue(callback){ 
    $.nette.ajax({ 
     url: "http://example.com/request", 
     contentType: 'application/json', 
     dataType: 'json', 
     success: function(payload) { 
      callback(playload); 
     } 
    }); 
}