function getBodyScrollTop()
{
	return self.pageYOffset || (document.documentElement && document.documentElement.scrollTop) || (document.body && document.body.scrollTop);
}

function getBodyScrollLeft()
{
	return self.pageXOffset || (document.documentElement && document.documentElement.scrollLeft) || (document.body && document.body.scrollLeft);
}

function setCookie(name, value)
{
    var valueEscaped = escape(value);
    var expiresDate = new Date();
    expiresDate.setTime(expiresDate.getTime() +  365  *  24  *  60  *  60  *  1000 ); // срок -  1  год, но его можно изменить
    var expires = expiresDate.toGMTString();
    var newCookie = name + "=" + valueEscaped + "; path=/; expires=" + expires;
    if (valueEscaped.length <=  4000 ) document.cookie = newCookie + ";";
}
function getCookie(name)
{
    var prefix = name + "=";
    var cookieStartIndex = document.cookie.indexOf(prefix);
    if (cookieStartIndex == - 1 ) return null;
    var cookieEndIndex = document.cookie.indexOf(";", cookieStartIndex + prefix.length);
    if (cookieEndIndex == - 1 ) cookieEndIndex = document.cookie.length;
    return unescape(document.cookie.substring(cookieStartIndex + prefix.length, cookieEndIndex));
} 

<button onClick="setCookie(coord,y)"> 123 </button>
<button onClick="alert(getCookie(coord,y))"> 123 </button>