jquery 手册
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回调对象(Callbacks ..
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Returns: BooleanBoolean .callbacks.has( Function callback )

描述: 判断回调列表中是否包含给定的函数。
  • version added: 1.7
  • .callbacks.has( Function callback )
  • callback 需要查找的函数。

Example

callbacks.has()方法判断回调列表中是否包含给定的函数:

// 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

Examples: