js全局变量在其他方法中赋值后无法影响到该方法外的全局变量的值（奇葩问题）

$(document).ready(function(){ 
     
    var strCookie=document.cookie;
    username="1";
    if (strCookie) {
        cookieVariables = strCookie.split(";");
        for (i = 0; i < cookieVariables.length; i++) {
        cookieName = cookieVariables[i].split("=");
        if (cookieName[0] === "username"){
            username=cookieName[1];
            alert(cookieName[1]);
        }   
    }
}
alert(username);
});

$(document).ready(function(){ 
     
    var strCookie=document.cookie;
    username=getname(username);
    function getname(username){ 
   
        if (strCookie) {
            cookieVariables = strCookie.split(";");
            for (i = 0; i < cookieVariables.length; i++) {
                cookieName = cookieVariables[i].split("=");
                if (cookieName[0] === username){
                   return cookieName[1];
                   alert("cookieName[1]");
                }       
            }
        }else{
            return "1";
        }
    }
alert(username);
});