Set device height on mobile

var mobile = window.matchMedia("(max-width: 768px)");
var $home_hero = $('#home_hero');
var $hero_mobile = $('.hero-mobile')

function setHomeHeight() {
   if (mobile.matches) {
      vh = window.innerHeight
      $home_hero.height(vh)
      $hero_mobile.height(vh)
      console.log('height has been set')
   } else {

      $hero_mobile.css({'height': ''})
      console.log('height has been UNset')
   }
}

$(document).ready(function() {
   setHomeHeight()
})