function modifyCart( isbn ){
	if( getObject( "q_"+ isbn ) ) {
		location.href="addToCart.asp?isbn="+ isbn + "&quantity="+ getObject( "q_"+ isbn ).value;
		return false;
	} else {
		return true;
	};
};

function getObject( id ){
	return ( document.getElementById ) ? document.getElementById( id ) : document.all[id];
}

function openImage( isbn ){
	var image = window.open( 'image.asp?isbn='+ isbn, '_productImage', 'toolbars=0,status=0,location=0' );
	
	try{
		image.focus();
	} catch( e ) {
		//ignore
	};
	
	return false;
};

function showFrames() {
	if( parent.window.frames.length == 0 ){
		if( window.location.pathname.indexOf( '/toc.html' ) == -1 ){
			parent.location.href = "/catalogus.html?page="+ window.location.pathname;
		} else {
			parent.location.href = "/catalogus.html";
		};
	};
};