给span标签赋值

//js代码

var tt = "某某某"; //这是登录后存入cookie来显示谁谁谁登录的变量

if (tt != null) {
var sp = document.getElementById("sp"); //id选择器的id为sp
sp.innerHTML = tt;
} else {
var sp = document.getElementById("sp");
sp.innerHTML = "admin"; //如果没登录则默认显示admin
}