<!DOCTYPE html>
<html>
<head>
<script>
function id_1(a){
var id = document.getElementById(a);
if (id.innerHTML==="innerHTML2"){
id.innerHTML="innerHTML1";
}
else if (id.innerHTML==="innerHTML1"){
id.innerHTML="innerHTML2";
}
}
</script>
</head>
<body>
<a id="id" href="javascript:id_1('id')">innerHTML1</a>
</body>
</html>