tribute( 'readonly' );
        this.display.focus();
        this.display.select();

        this.editingDigits = this.display.value.replace( ':', '' ).padStart( 4, '0' );
      }

      handleTimerInput( e ) {
        if ( this.display.hasAttribute( 'readonly' ) ) return;

        if ( e.key === 'Enter' ) {
          this.display.blur();
          return;
        }

        if ( !/^\d$/.test( e.key ) &&
          !['Backspace', 'Delete', 'ArrowLeft', 'ArrowRight', 'Tab', 'Escape'].includes( e.key ) ) {
   