How to set navigation class on current page

support
2 
{{ if eq $currentPage . }} class="nav-link active" aria-current="page" {{ end }}

So full code is:

{{ $currentPage := . -}}
{{ range .Site.Menus.main -}}
  <li class="nav-item">
      <a class="nav-link" href="{{ .URL | relLangURL }}" {{ if eq $currentPage . }} class="nav-link active" aria-current="page" {{ end }}>{{ .Name }}</a>
  </li>
{{ end -}}