Using TS rendering

UsingAjaxUrl.html

{namespace t=Helhum\TyposcriptRendering\ViewHelpers}

<button class="ajax-button" data-ajaxUri="{t:uri.ajaxAction(action: 'foo', controller: 'bar') -> f:format.htmlentities()}">
  Click Me
</button>

<script type="text/javascript">
  jQuery.ajax(
    jQuery(".ajax-button").data("ajaxUri")
  ).done(
    function(result) {
      console.log(result);
    }
  );
</script>