[Nexus]

<form action="/search/node/" method="get" id="searchform">
	<span class="icon"><i class="fa fa-search"></i></span>
	<input type="search" id="search" placeholder="Поиск..." />
	<input type="submit">
</form>
<script>
  document.getElementById('search').addEventListener('input',function(){
      var form=document.getElementById('searchform');
      form.action=form.action.replace(/(\/search\/node\/).+/,'$1')+this.value;
      console.log(form.action);
  });
</script>