callbacks.has()

类别: 回调对象

callbacks.has( [callback ] )返回值: 布尔值

描述: 确定列表中是否附加了任何回调函数。如果提供回调函数作为参数，则确定它是否在列表中。

示例

使用 callbacks.has() 检查回调列表是否包含特定回调函数

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// A sample logging function to be added to a callbacks list
var foo = function( value1, value2 ) {
  console.log( "Received: " + value1 + "," + value2 );
};
 
// A second function which will not be added to the list
var bar = function( value1, value2 ) {
  console.log( "foobar" );
};
 
var callbacks = $.Callbacks();
 
// Add the log method to the callbacks list
callbacks.add( foo );
 
// Determine which callbacks are in the list
console.log( callbacks.has( foo ) );
// true
console.log( callbacks.has( bar ) );
// false