请高手帮我简化下面的代码

要达到的目标是，其中一个图层可见，其他两个隐藏，以及其中一个有中间线，另外两个没有。


function nav(){
var na1 = document.getElementById("nv1");
var na2 = document.getElementById("nv2");
var na3 = document.getElementById("nv3");
var ls1 = document.getElementById("li1");
var ls2 = document.getElementById("li2");
var ls3 = document.getElementById("li3");

ls1.onclick=function() {
ls1.style.textDecoration="line-through";
ls2.style.textDecoration="none";
ls3.style.textDecoration="none";
na1.style.display="block";
na2.style.display="none";
na3.style.display="none";
}

ls2.onclick=function() {
ls1.style.textDecoration="none";
ls2.style.textDecoration="line-through";
ls3.style.textDecoration="none";
na1.style.display="none";
na2.style.display="block";
na3.style.display="none";
}

ls3.onclick=function() {
ls1.style.textDecoration="none";
ls2.style.textDecoration="none";
ls3.style.textDecoration="line-through";
na1.style.display="none";
na2.style.display="none";
na3.style.display="block";
}
}

window.onload=nav;