classList如何实现两个按钮样式切换

<p class="login-title">
<a href="javascript:void(0)" rel="external nofollow" rel="external nofollow" class="mya1" id="mya" onclick="myonclick()">注册</a>
<a href="javascript:void(0)" rel="external nofollow" rel="external nofollow" class="mya2" id="myaa" onclick="myonclick1()">登陆</a>
</p>

funcction myonclick(){
document.getElementById("mya").classList.remove("newClassName1");
document.getElementById("myaa").classList.remove("newClassName");
}
function myonclick1(){
document.getElementById("mya").classList.add("newClassName1");
document.getElementById("myaa").classList.add("newClassName");
}

.login-title{
width:200px;
height:200px;
margin: 0 auto;
background-color:antiquewhite;
}
.mya2{
padding: 0 20px 10px 20px;
color:#FFFFFF;
font-size:22px;
text-decoration:none;
}
.mya1{
padding:0 20px 10px 20px;
color:#7F4A88;
font-size:22px;
text-decoration:none;
border-bottom:2px solid #7F4A88;
}
.newClassName{
padding:0 20px 10px 20px;
color:#7F4A88;
font-size:22px;
text-decoration:none;
border-bottom:2px solid #7F4A88;
}
.newClassName1{
padding: 0 20px 10px 20px;
color:#FFFFFF;
font-size:22px;
text-decoration:none;
}