jQuery callbacks.fired() 方法

jQuery callbacks.fired() 方法用于检查回调是否已经至少被调用过一次。此方法返回布尔值。

句法：

callbacks.fired()

参数：此方法不接受任何参数。

返回值：此方法返回一个布尔值。

示例 1：此示例返回 true，因为至少调用了一次 fire() 方法。

  

    
    

  

    
        GeeksForGeeks
    
  
    
        JQuery | callbacks.fired() method
    
  
    
        click here
    
      
    
  
    
        var el_down = document.getElementById("GFG_DOWN");
        var res = "";
        var callbacks = jQuery.Callbacks();
  
        function Geeks() {
  
            // First function to be added to the list
            var fun1 = function (val) {
                res = res + "This is function 1 and"
                    + " value passed is " + val + "<br>";
            };
  
            // Adding the function 1
            callbacks.add(fun1);
              
            // Calling with "GFG_1"
            callbacks.fire("GFG_1");
              
            // Calling callbacks.fired()
            // method to get true
            el_down.innerHTML = callbacks.fired();
        } 
    

  

输出：

示例 2：此示例返回 false，因为尚未调用 fire() 方法。

  

    
    

  

    
        GeeksForGeeks
    
  
    
        JQuery | callbacks.fired() method
    
  
    
        click here
    
      
    
  
    
        var el_down = document.getElementById("GFG_DOWN");
        var res = "";
        var callbacks = jQuery.Callbacks();
  
        function Geeks() {
  
            // First function to be added to the list
            var fun1 = function (val) {
                res = res + "This is function 1 and"
                + " value passed is " + val + "<br>";
            };
  
            // Adding the function 1
            callbacks.add(fun1);
              
            // Adding again
            callbacks.add(fun1);
              
            // Calling callbacks.fired() but 
            // This time we will get false
            el_down.innerHTML = callbacks.fired();
        } 
    

  

输出：