Question

所属分类：回调对象

callbacks.has( callback )返回: Boolean

描述: 确定列表中是否提供一个回调

• 添加的版本: 1.7callbacks.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