datahub/wherehows-web/app/components/dataset-table-column.js

import Ember from 'ember';
const {
  Component,
  computed
} = Ember;

export default Component.extend({
  tagName: 'th',
  classNameBindings: ['isColumnActive'],
  columnName: '',
  sortColumnWithName: '',
  sortDirection: null,

  isColumnActive: computed('sortColumnWithName', 'columnName', function () {
    const {sortColumnWithName, columnName} = this.getProperties('sortColumnWithName', 'columnName');
    return sortColumnWithName && sortColumnWithName === columnName;
  }),

  click() {
    const {
      columnName,
      sortDirection,
      isColumnActive
    } = this.getProperties('columnName', 'sortDirection', 'isColumnActive');

    if (columnName) {
      let updatedSortDirection;
      // if this column is not active, default sort direction to ascending, else toggle sort direction
      if (!isColumnActive) {
        updatedSortDirection = 'asc';
      } else {
        updatedSortDirection = sortDirection === 'asc' ? 'desc' : 'asc';
      }

      this.get('sortDidChange')(columnName, updatedSortDirection);
      this.set('sortDirection', updatedSortDirection);
    }
  }
});