https://www.townofcolumbianc.com/repository/designs/parts/scripts/random.js

1// Random number insertion library
2// requires jQuery
3//
4// put this in design xml file
5//		<JSInclude library="random.js" />		
6//
7// you call it as:
8// Random.image(6, '<img id="photos" src="{$imagePath}/photos1.jpg" alt="photos of Otsego, MN" />');
9// or
10// Random.className(6, 'myBox');
11//
12// in the className method, default class on the box should always be "random1" to
13// provide a default and prevent a FOUC
14
15var Random = new (function Random() {
16
17	// PUBLIC METHODS
18	
19	// * use "cram" to force a number, rather than use a random one
20	// * each returns the number it selected
21
22	// takes a number and a string containing a valid, default image
23	// tag, randomizes the numeral "1" in the last pathname piece and
24	// spits out the finished tag
25	this.image = function randomImage(max, imageTag, cram) {
26		var $img = $(imageTag);
27		var n = (cram != null ? setSrc(cram, $img) : randomSrc(max, $img));
28		// put it in a dummy shell so we can get its contents as an
29		// HTML string
30		document.write(($("<div />").append($img)).html());
31		document.close();
32
33		return n;
34	};
35
36	// adds a class to the given element called "randomX", where X is the random integer
37	this.className = function randomClassName(max, id, cram) {
38		var $e = $("#" + id);
39		var n = (cram != null ? cram : randomNumber(max));
40		if ($e.hasClass("random1")) {
41			$e.removeClass("random1");
42			$e.addClass("random" + n);
43		}
44
45		return n;
46	};
47
48	// replaces "random1" in the style att. on all elements matching the selector
49	this.style = function randomStyle(max, selector, cram) {
50		var $e = $(selector);
51		var n = (cram != null ? cram : randomNumber(max));
52		$e.each(function() {
53			$(this).attr("style", $(this).attr("style").replace("random1", "random" + n));
54		});
55
56		return n;
57	};
58
59
60
61	// INTERNAL FUNCTIONS
62	
63	// replaces the numeral "1" with the requested random number in an
64	// image's src attribute
65	function randomSrc(max, element) {
66		var n = randomNumber(max);
67		setSrc(n, element);
68		return n;
69	}
70
71	function setSrc(n, element) {
72		var $img = (typeof element == "string" ? $("#" + id) : $(element));
73		var newSrc = $img.attr("data-src") ? $img.attr("data-src") : $img.attr("src");
74		var lastslash = newSrc.lastIndexOf('/');
75		var part1 = newSrc.substr(0, lastslash);
76		var part2 = newSrc.substr(lastslash);
77		
78		part2 = part2.replace('1', n);
79		$img.attr('src', (part1 + part2));
80		
81		return n;
82	}
83
84	// returns a random number between 1 and max
85	function randomNumber(max) {
86		return Math.ceil(Math.random() * max);
87	}
88
89	// test harness for randomness
90	function random_testDistribution() {
91		var arr = [0,0,0,0,0];
92		for(i = 1; i < 10; i++) {
93			var rand = randomNumber(5);
94			arr[rand - 1]++;
95		}
96		console.log(arr);
97	}
98})();