gistfile1.js

var ownDomain = location.hostname,
  referrerDomain = document.referrer.split('/')[2],
	author = '';

if ( ownDomain != referrerDomain) {
	var script = document.createElement('script');
	script.src = '//javascript.mamp/json/?callback=setAuthorCookie';
	document.getElementsByTagName('head')[0].appendChild(script);
}
// var author = getCookie( 'partnerOptimizerId' );

function setAuthorCookie( data ) {
	var exdate = new Date(),
		exdays = 1,
		value = data['userId'],
		cookie = 'partnerOptimizerId',
		exdate = new Date();
	
	var author = value;

	exdate.setDate(exdate.getDate() + exdays);
	var c_value=escape(value) + ((exdays==null) ? "" : "; expires="+exdate.toUTCString());
	document.cookie=cookie + "=" + c_value;
	console.log( author );
}

console.log( author );