discourse/app/assets/javascripts/discourse/components/d-section.js.es6

import DiscourseURL from 'discourse/lib/url';

// Can add a body class from within a component, also will scroll to the top automatically.
export default Ember.Component.extend({
  tagName: 'section',

  _scrollTop() {
    if (Ember.testing) { return; }
    $(document).scrollTop(0);
  },

  didInsertElement() {
    this._super();

    const pageClass = this.get('pageClass');
    if (pageClass) {
      $('body').addClass(`${pageClass}-page`);
    }

    const bodyClass = this.get('bodyClass');
    if (bodyClass) {
      $('body').addClass(bodyClass);
    }

    if (this.get('scrollTop') === "false") {
      return;
    }

    if (DiscourseURL.isJumpScheduled()) { return; }
    Ember.run.scheduleOnce('afterRender', this, this._scrollTop);
  },

  willDestroyElement() {
    this._super();
    const pageClass = this.get('pageClass');
    if (pageClass) {
      $('body').removeClass(`${pageClass}-page`);
    }

    const bodyClass = this.get('bodyClass');
    if (bodyClass) {
      $('body').removeClass(bodyClass);
    }
  }
});