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 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