jQuery callbacks.lock()方法

jQuery中的callbacks.lock()方法是用来锁定一个回调列表的状态。

语法:

callbacks.lock()

返回值：该方法返回它所连接的回调对象。

例子1：这个例子首先添加并启动函数，然后锁定回调列表，然后再次添加并启动函数。

<!DOCTYPE HTML>
<html>
  
<head>
    <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>
        JQuery | callbacks.lock() method
    </p>
      
    <button onclick="Geeks();">
        click here
    </button>
      
    <p id="GFG_DOWN"></p>
  
    <script>
        var el_down = document
                .getElementById("GFG_DOWN");
                  
        var res = "";
        var callbacks = jQuery.Callbacks();
        function Geeks() {
            var func = function (val) {
                res = res + 
                    "value passed is - " + val;
            };
  
            // Function added to list
            callbacks.add(func);
            callbacks.fire("gfg_1");
  
            // Locking the callback list
            callbacks.lock(); 
  
            // Function again added to list
            callbacks.add(func); 
            callbacks.fire("gfg_2");
            el_down.innerHTML = res;
        } 
    </script>
</body>
  
</html>

输出:
jQuery callbacks.lock()方法

例子2：这个例子提供了一个按钮来锁定列表，然后添加并启动函数来检查该方法是否有效。

<!DOCTYPE HTML>
<html>
  
<head>
    <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>
        JQuery | callbacks.lock() method
    </p>
  
    <button onclick="Geeks();">
        click here
    </button>
      
    <button onclick="lock();">
        lock here
    </button>
      
    <p id="GFG_DOWN"></p>
  
    <script>
        var el_down = document
                .getElementById("GFG_DOWN");
  
        var res = "";
        var callbacks = jQuery.Callbacks();
        function lock() {
            callbacks.lock();
        }
        function Geeks() {
  
            // Function to be added to the list
            var fun = function (val) {
                res = res + "This is function and "
                + "value passed is " + val + "<br>";
            };
  
            callbacks.add(fun); // Adding
            callbacks.fire("GFG_1");
            el_down.innerHTML = res;
        } 
    </script>
</body>
  
</html>

输出:
jQuery callbacks.lock()方法