/* background image */

function preload(arrayOfImages) {
    $(arrayOfImages).each(function(){
        $('<img/>')[0].src = this;
        // Alternatively you could use:
        // (new Image()).src = this;
    });
}
preload([
    '/img/bg_flash.jpg',
    '/img/bg_flash1.jpg',
    '/img/bg_flash2.jpg',
    '/img/bg_flash3.jpg',
    '/img/bg_flash4.jpg',
]);

$(function(){
	var nowImage;
	var nowDate = new Date();
	var nowMonth = nowDate.getMonth() + 1;
	
	if( nowMonth >= 4 && nowMonth <= 6 ) {
		nowImage = "/img/bg_flash1.jpg";
	} else if( nowMonth >= 7 && nowMonth <= 9 ) {
		nowImage = "/img/bg_flash2.jpg";
	} else if( nowMonth >= 10 && nowMonth <= 12 ) {
		nowImage = "/img/bg_flash3.jpg";
	} else if( nowMonth >= 1 && nowMonth <= 3 ) {
		nowImage = "/img/bg_flash4.jpg";
	} else {
		nowImage = "/img/bg_flash.jpg";
	}

	var thisMonthImage = "url(" + nowImage + ")";
	$("#bg_flash").css("background", thisMonthImage);
});