在“用户名” cookie中

Question

我一直试图制作一个记住用户名的“用户名” cookie。但是，我不明白为什么while循环必须搜索空格。

function getCookie(cname) {
    var name = cname + "=";
    var decodedCookie = decodeURIComponent(document.cookie);

    var ca = decodedCookie.split(';');
    for(var i = 0; i < ca.length; i++) {
        var c = ca[i];
        while (c.charAt(0) == ' ') {
            c = c.substring(1);
        }
        if (c.indexOf(name) == 0) {
            return c.substring(name.length, c.length);
        }`enter code here`
    }
    return "";
    }

这是检查Cookie的功能

function checkCookie() {
    var user=getCookie("username");

    if (user != "") {
        alert("Welcome again " + user);
    } else {
       user = prompt("Please enter your name:","");
       if (user != "" && user != null) {
           setCookie("username", user, 30);
       }
    }
}

并设置cookie

function setCookie(cname,cvalue,exdays) {
    var d = new Date();
    d.setTime(d.getTime() + (exdays*24*60*60*1000));
    var expires = "expires=" + d.toGMTString();
    document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/";
}