### 返回值:Booleancallbacks.has(callback) ### 概述 確定是否提供的回調列表 ### 參數 #### **callback***V1.7* 用來搜索的回調。 ### 示例 #### 描述: 用?callbacks.has()?檢查是否回調列表中包含一個特定的回調: ##### jQuery 代碼: ~~~ // 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 ~~~