function PhotoBrowser(slidesCount) {
	
	this.currentSlideId = 1;
	this.slidesCount = slidesCount;
	//this.slides = new Array();
	
	// initialize
	this.init = function () {
		// show 1st slide
		document.getElementById('slide-1').style.visibility = 'visible';
	}
	
	
	this.showPrevious = function () {
		// displays the previous slide if it exists
		if (this.currentSlideId == 1) return;	// already showing the first slide, so no previous to show
		// determine current slide's DOM code
		currentSlide = "slide-" + this.currentSlideId;
		// make current slide hidden
		document.getElementById(currentSlide).style.visibility = 'hidden';
		// change current slide to previous slide
		this.currentSlideId --;
		currentSlide = "slide-" + this.currentSlideId;
		// make current slide visible
		document.getElementById(currentSlide).style.visibility = 'visible';
	}
	
	this.showNext = function () {
		// displays the next slide if it exists
		if (this.currentSlideId == this.slidesCount) return;	// already showing the last slide, so no next to show
		// determine current slide's DOM code
		currentSlide = "slide-" + this.currentSlideId;
		// make current slide hidden
		document.getElementById(currentSlide).style.visibility = 'hidden';
		// change current slide to next slide
		this.currentSlideId ++;
		currentSlide = "slide-" + this.currentSlideId;
		// make current slide visible
		document.getElementById(currentSlide).style.visibility = 'visible';
	}
}