jQuery deferred.then()用法及代碼示例

JQuery中的deferred.then()方法用於添加處理程序，這些處理程序在解析，拒絕或進行Deferred對象時將被調用。

用法:

deferred.then(doneCallbacks[, failCallbacks][, progressCallbacks])

參數：

doneCallbacks:這是一個函數或函數數組，在解析Deferred時會調用此函數。
failCallbacks:這是一個函數或函數數組，在拒絕Deferred時會調用它。
progressCallbacks:這是一個函數或函數數組，在將進度通知發送到Deferred對象時會調用此函數。

返回值：此方法方法返回延遲的對象。

下麵討論了兩個示例：

例：在此示例中，使用notify and resolve方法調用then()方法。

<!DOCTYPE HTML>  
<html>   
<head>  
    <title>  
      JQuery | deferred.then() method 
    </title> 
    <script src="https://code.jquery.com/jquery-3.5.0.js"> 
</script>  
</head>    
<body style="text-align:center;"> 
    <h1 style="color:green;">   
        GeeksForGeeks   
    </h1>  
    <p id="GFG_UP">  
    </p> 
    <button onclick = "Geeks();"> 
    click here 
    </button> 
    <p id="GFG_DOWN">  
    </p> 
    <script>  
        var el_up = document.getElementById("GFG_UP"); 
        el_up.innerHTML = "JQuery | deferred.then() method"; 
        function Func1(val, div){ 
          $(div).append("From doneCallbacks - " + val); 
        } 
        function Func2(val, div){ 
          $(div).append("From failCallbacks - " + val); 
        } 
        function Func3(val, div){ 
          $(div).append("From progressCallbacks - " + val); 
        } 
        function Geeks() { 
            var def = $.Deferred(); 
            def.then(Func1, Func2, Func3); 
            def.notify('Deferred "def" is notified.<br/>' 
                     , '#GFG_DOWN'); 
            def.resolve('Deferred "def" is resolved.<br/>' 
                     , '#GFG_DOWN'); 
        }  
    </script>  
</body>    
</html>

輸出：

例：在此的示例then()方法被稱為通知和拒絕方法。

<!DOCTYPE HTML>  
<html>   
<head>  
    <title>  
      JQuery | deferred.then() method 
    </title> 
    <script src="https://code.jquery.com/jquery-3.5.0.js"> 
    </script>  
</head>    
<body style="text-align:center;"> 
    <h1 style="color:green;">   
        GeeksForGeeks   
    </h1>  
    <p id="GFG_UP">  
    </p> 
    <button onclick = "Geeks();"> 
    click here 
    </button> 
    <p id="GFG_DOWN">  
    </p> 
    <script>  
        var el_up = document.getElementById("GFG_UP"); 
        el_up.innerHTML = "JQuery | deferred.then() method"; 
        function Func1(val, div){ 
          $(div).append("From doneCallbacks - " + val); 
        } 
        function Func2(val, div){ 
          $(div).append("From failCallbacks - " + val); 
        } 
        function Func3(val, div){ 
          $(div).append("From progressCallbacks - " + val); 
        } 
        function Geeks() { 
            var def = $.Deferred(); 
            def.then(Func1, Func2, Func3); 
            def.notify('Deferred "def" is notified.<br/>', 
                       '#GFG_DOWN'); 
            def.reject('Deferred "def" is rejected.<br/>', 
                       '#GFG_DOWN'); 
        }  
    </script>  
</body>    
</html>

輸出：

相關用法

注：本文由純淨天空篩選整理自PranchalKatiyar大神的英文原創作品 JQuery deferred.then() method。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。