callbacks.has()
确定列表是否有绑定任何回调。如果回调作为一个参数提供,那么可以确定其是否在列表中。
callbacks.has(callback)
callback。类型: Function()。用来查找的回调函数。
例子
使用callbacks.has()
检查列表中是否提供一个回调:
// a sample logging function to be added to a callbacks listvar foo =function ( value1, value2 ) { console.log( "Received: " + value1 + "," + value2 ); }; // a second function which will not be added to the listvar 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