Angular sorting (methods in TypeScript file)

students.component.ts

sortTable(prop: string) {
   this.path = prop.split('.');
   this.order = this.order * (-1); 
   return false; 
 }
 
getIcon(prop:string): string{
  //Yo uso iconos font-awesome de ahí la nomenclatura
   var iconClass = "fa fa-sort";

    if(this.path.indexOf(prop) != -1)
    {
     iconClass = this.order===-1 ? 'fa fa-sort-down' : 'fa fa-sort-up';
    }

    return iconClass;
 }