callbacks.has( [callback ] )Returns: Boolean

Description: Determine whether or not the list has any callbacks attached. If a callback is provided as an argument, determine whether it is in a list.

version added: 1.7callbacks.has( [callback ] )
- callback
  
  The callback to search for.

Example:

Use callbacks.has() to check if a callback list contains a specific callback:

// 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

callbacks.has( [callback ] )Returns: Boolean

version added: 1.7callbacks.has( [callback ] )