Multi Sorting in TS

sortArrObjects(
    key: string,
    order: string = 'asc',
    isDate: boolean = false
  ) {
    return (a, b) => {
      if (!a.hasOwnProperty(key) || !b.hasOwnProperty(key)) {
        // if property doesn't exist on either object
        return 0;
      }

      let varA;
      let varB;
      if (isDate) {
        varA = new Date(a[key]);
        varB = new Date(b[key]);
      } else {
        varA = typeof a[key] === 'string' ? a[key].toUpperCase() : a[key];
        varB = typeof b[key] === 'string' ? b[key].toUpperCase() : b[key];
      }

      let comparison = 0;
      if (varA > varB) {
        comparison = 1;
      } else if (varA < varB) {
        comparison = -1;
      }
      return order === 'asc' ? comparison * -1 : comparison;
    };
  }