javascript duty 'get component progenitor class' assign

my difficulty sincerely simple: duty gets id 'this' <li> component formed progenitor id <ul>. used work glorious nonetheless any more, i presumably need have <ul> classes instead id while still being means distribute id 'current' tide element, change css.

function myfunction(element) {
  liarray = document.getelementbyid("leftlist").childnodes;
  i = 0;
  while (liarray[i]) {
    liarray[i].id = "";
    i++;
  }
  element.id = "current"; // element.classname  ?
}

ul#leftlist {
  background-color: rgb(205, 205, 205);
}

ul#leftlist li#current {
  color: rgb(96, 176, 255);
  background-color: 218, 218, 218);
}

ul#leftlist li {
  color: rgb(86, 86, 86);
}

#leftlist a:link {
  color: rgb(86, 86, 86);
  background-color: #ddd;
}

#leftlist a:active {
  color: rgb(96, 176, 255);
  background-color: rgb(218, 218, 218);
}

<ul id="leftlist">
  <li onclick='myfunction(this);'>
    <a href="123" bla bla </a></li>
  <li onclick='myfunction(this);'> .... etc.</li>
</ul>

perhaps i need change css. worked before nonetheless tide id being effective ul#leftlist li a takes priority even i distribute id="current" around javascript.