callbacks.has.xml

<?xml version="1.0"?>
<entry name="callbacks.has" type="method" return="Boolean">
  <title>callbacks.has()</title>
  <signature>
    <added>1.7</added>
    <argument name="callback" type="Function" optional="true">
      <desc>The callback to search for.</desc>
    </argument>
  </signature>
  <desc>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.</desc>
  <longdesc/>
  <example>
    <desc>Use <code>callbacks.has()</code> to check if a callback list contains a specific callback:</desc>
    <code><![CDATA[
// 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
]]></code>
  </example>
  <category slug="callbacks-object"/>
  <category slug="version/1.7"/>
</entry>