Get a randomized extract of a flickr set, for gallery purposes

flickr.js

var flickr = {
	apiKey: null,
	photosetId: null,
	photos: null,
	ownerName: null,
	limit: null,
	init: function(apiKey, photosetId, limit) {
		this.apiKey = apiKey;
		this.photosetId = photosetId;
		this.limit = parseInt(limit);
		this.photos = this.getPhotos(this.decode());
		this.write(this.photos);
		return this;
	},
	decode: function() {
		var url = 'https://api.flickr.com/services/rest/?method=flickr.photosets.getPhotos&api_key='+flickr.apiKey+'&photoset_id='+flickr.photosetId+'&format=json&extras=url_m';
		var response = this.httpGet(url);
		var execute = 'this.'+response;
		return eval(execute);
	},
	jsonFlickrApi : function(code) {
		return code;
	},
	getPhotos : function(object) {
		this.ownerName = object.photoset.ownername;
		var photos = [];
		object.photoset.photo.forEach(function(element){
			photos.push([element.url_m, element.title]);
		});
		return photos;
	},
	httpGet: function(theUrl) {
		var xmlHttp = null;
		xmlHttp = new XMLHttpRequest();
		xmlHttp.open( "GET", theUrl, false );
		xmlHttp.send( null );
		return xmlHttp.responseText;
	},
	getRandomNumber: function() {
		return Math.floor((Math.random() * (this.photos.length -1)) + 1);
	},
	write: function(photos) {
		var html = '<div class="flickr_images">';

		for (var i = 0; i < this.limit; i++) {
			var random = this.getRandomNumber();
			html += '<img src="'+photos[random][0]+'" alt="'+photos[random][1]+'" />';
		}
		var flickUrl = 'https://www.flickr.com/photos/'+this.ownerName.toLowerCase()+'/sets/'+this.photosetId;
		html += '<div class="taken_from">Random '+this.limit+' photos taken from <a href="'+flickUrl+'" target="_blank">'+flickUrl+'</a></div>';
		html += '</div>';
		document.write(html);
	}
}

flickr.init('50b2c88d16b7d6765f8c2f9b9bce844f', '72157644508338618', 4);