Lumore

button {
   display: block;
}

<script>
export default {
  methods: {
    doAlert () {
      alert('Hi!')
    }
  },
  created () {
    window.addEventListener('scroll', () => {
      let body = document.getElementsByTagName('body')[0]
      if (window.scrollY > body.clientHeight) {
        this.doAlert()
      }
    })
  }
}
</script>

elems.map((item, index) => {
  item.textContent = index
})

elems.forEach(function(val, index) {
  elems[index].textContent = index;
});

::-moz-scrollbar
{
width: 0px;
height: 0px;
}

namespace frontend\widgets;
use vendor/yii-rbac-plus;

class YiiRbacPlus extends yii-rbac-plus {
    $config = [
        ['roles' => 'admin', 'user']
    ];  // Нерабочий код - только для примера
}