grafana/public/app/core/utils/outline.ts

// based on http://www.paciellogroup.com/blog/2012/04/how-to-remove-css-outlines-in-an-accessible-manner/
function outlineFixer() {
  const d: any = document;

  const style_element = d.createElement('STYLE');
  const dom_events = 'addEventListener' in d;

  const add_event_listener = function(type, callback) {
    // Basic cross-browser event handling
    if (dom_events) {
      d.addEventListener(type, callback);
    } else {
      d.attachEvent('on' + type, callback);
    }
  };

  const set_css = function(css_text) {
    // Handle setting of <style> element contents in IE8
    !!style_element.styleSheet ? (style_element.styleSheet.cssText = css_text) : (style_element.innerHTML = css_text);
  };

  d.getElementsByTagName('HEAD')[0].appendChild(style_element);

  // Using mousedown instead of mouseover, so that previously focused elements don't lose focus ring on mouse move
  add_event_listener('mousedown', function() {
    set_css(':focus{outline:0 !important}::-moz-focus-inner{border:0;}');
  });

  add_event_listener('keydown', function() {
    set_css('');
  });
}

outlineFixer();