ab.js

var $button = jQuery( '#my-button' ),
    test = Math.floor((Math.random()*2)+1);

if ( test == 1 )
    $button.css( 'background', '#ff0000' ).data( 'test-value', 'red' );
else
    $button.css( 'background', '#0000ff' ).data( 'test-value', 'blue' );

_gaq.push(['_trackEvent', 'My Button', 'Show', $button.data( 'test-value' )]);
$button.on( 'click', function() {
    _gaq.push(['_trackEvent', 'My Button', 'Click', $button.data( 'test-value' )]);
});