Mobile Menu Toggle Twenty Fifteen

Hi everyone,
I am trying to modify the Mobile toggle menu for the Twenty Fifteen theme so that the toggle affects #site-navigation instead of #secondary. Im pretty sure I have to modify this in the functions.js. I’m not exactly sure how to do this but this is the javascript

// Enable menu toggle for small screens.
 ( function() {
  var secondary = $( '#secondary' ), button, menu, widgets, social;
  if ( ! secondary ) {
   return;
  }

  button = $( '.site-branding' ).find( '.secondary-toggle' );
  if ( ! button ) {
   return;
  }

  // Hide button if there are no widgets and the menus are missing or empty.
  menu    = secondary.find( '.nav-menu' );
  widgets = secondary.find( '#widget-area' );
  social  = secondary.find( '#social-navigation' );
  if ( ! widgets.length && ! social.length && ( ! menu || ! menu.children().length ) ) {
   button.hide();
   return;
  }

  button.on( 'click.twentyfifteen', function() {
   secondary.toggleClass( 'toggled-on' );
   secondary.trigger( 'resize' );
   $( this ).toggleClass( 'toggled-on' );
  } );
 } )();

I’m not fluent in Javascript but this is what I have so far.

// Enable menu toggle for small screens.
 ( function() {
  var sitenav = $( '#site-navigation' )/*, button, menu, widgets, social*/;
  if ( ! sitenav ) {
   return;
  }

  button = $( '.site-branding' ).find( '.secondary-toggle' );
  if ( ! button ) {
   return;
  }

  // Hide button if there are no widgets and the menus are missing or empty.
  /*menu    = secondary.find( '.nav-menu' );
  widgets = secondary.find( '#widget-area' );
  nav  = secondary.find( '#site-navigation' );
  social  = secondary.find( '#social-navigation' );
  if ( ! widgets.length && ! social.length && ( ! menu || ! menu.children().length ) ) {
   button.hide();
   return;
  }*/

  button.on( 'click.twentyfifteen', function() {
   sitenav.toggleClass( 'toggled-on' );
   sitenav.trigger( 'resize' );
   $( this ).toggleClass( 'toggled-on' );
  } );
 } )();

I am using a child theme and I know how to remove the old function and add my new function in the functions.php. I am just having trouble with this part specifically. I would appreciate any help concerning this.

p.s my current code results in a nonfunctional button. 🙁

Thanks in advance