Question

Let’s say, I’ve a input button like this:

<code>
<input type="submit" value="Submit" onclick="fxn1();fxn2();fxn3();"/>
</code>  

Now, i wan’t to add a new function fxn() (prepend or append) to the list of functions already assigned to onclick event. How would I do that? Also, the number of functions assigned to onclick is not known and hence can be anything greater than 0 or even 0 sometimes.

Answer 1

jQuery.Callbacks do the needful. introduces in jQuery v1.7

The following are two sample methods named fn1 and fn2:

function fn1( value ){
    console.log( value );
}

function fn2( value ){
    fn1("fn2 says:" + value);
    return false;
}    

// Supported Flags : 
// once: Ensures the callback list can only be fired once (like a Deferred).

var callbacks = $.Callbacks( "once" );
callbacks.add( fn1 );
callbacks.fire( "foo" );
callbacks.add( fn2 );
callbacks.fire( "bar" );
callbacks.remove( fn2 );
callbacks.fire( "foobar" );

Reference