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JQuery when() method

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This JQuery.when() method in JQuery  gives a way to execute callback functions depending on zero or more Thenable objects, which usually are Deferred objects that represent asynchronous events.

Syntax:

jQuery.when(deferreds)

    Parameters:

  • deferreds: This parameter specifies zero or more Thenable objects.

Return Value: This method returns a Promise.

There are two examples discussed below:

  • Example: In this example, the Deferred() is used to create a new object and after that then() method is called with notify and resolve method.




    <!DOCTYPE HTML> 
    <html>  
    <head>
    </script
    </head>   
    <body style="text-align:center;">
        <h1 style="color:green;">  
            GeeksForGeeks  
        </h1
        <p>
        JQuery.when() method
        </p>
        <button onclick = "Geeks();">
        click here
        </button>
        <p id="GFG_DOWN"
        </p>
        <script>
            var def = $.Deferred();
            function Geeks() {
                $.when().then(function(a) {
                alert(
                "when() method called this alert()." );
                });
            
        </script
    </body>   
    </html>        

    
    

    Output:
    Before clicking on button:

    After clicking on button:

    • Example: In this example, the Deferred() method is used and the state of Deferred object is checked.




      <!DOCTYPE HTML> 
      <html>  
      <head>
      </script
      </head>   
      <body style="text-align:center;">
          <h1 style="color:green;">  
              GeeksForGeeks  
          </h1
          <p>
          JQuery.when() method 
          </p>
          <button onclick = "Geeks();">
          click here
          </button>
          <p id="GFG_DOWN"
          </p>
          <script>
              var def = $.Deferred();
              function Geeks() {
                  $.when(def).done(function (x) {
                      $('#GFG_DOWN').append(
                       'when() method is executed.')
                  });
                  def.resolve();
              
          </script
      </body>   
      </html>                

      
      

      Output:



    Last Updated : 16 Jul, 2020
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