Callback Function In Javascript

<script>

function hello(c){

alert(c);

}

// commong calling.

hello('Good Afternoon');

// not call back function. Just alerting the caller function literally;

hello( function(){ alert('Holla'); return 'Good Morning'; } );

// callback and ononymous function. First alerting 'Holla',

// then 'Good Evening'

hello( (function(){ alert('Holla'); return 'Good Evening'; })());

</script>

Callback Function In Javascript