que hace document.cookie.split

// Split a cookie string into an array of cookie [name, value] pairs
var cookiePairs = document.cookie.split(';');
 
// For each cookie pair
for(var i = 0; i < cookiePairs.length; i++) {
    // Split into an array of name and value
    var nameValue = cookiePairs[i].split('=');
 
    // Assign the cookie name and value to variables
    var name = nameValue[0];
    var value = nameValue[1];
 
    // Do something with the cookie value
    console.log(value);
}