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<!DOCTYPE html>
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<link rel="stylesheet" href="" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
<meta charset="utf-8" />
body { padding:1em }
h2 { margin-top:2em }
<main role="main" class="container">
<h1>Deterministisk fikagruppsgenerator</h1>
<p class="lead">Nya grupper slumpas automatiskt baserat på veckonummer.</p>
<div id="groups" class="row"></div>
// the following adds the Math.seedrandom() function, making random() deterministic if given the same seed. (Technically I believe it was always deterministic, but not in a useful way.)
!function(a,b,c,d,e,f,g,h,i){function j(a){var b,c=a.length,e=this,f=0,g=e.i=e.j=0,h=e.S=[];for(c||(a=[c++]);d>f;)h[f]=f++;for(f=0;d>f;f++)h[f]=h[g=s&g+a[f%c]+(b=h[f])],h[g]=b;(e.g=function(a){for(var b,c=0,f=e.i,g=e.j,h=e.S;a--;)b=h[f=s&f+1],c=c*d+h[s&(h[f]=h[g=s&g+b])+(h[g]=b)];return e.i=f,e.j=g,c})(d)}function k(a,b){var c,d=[],e=typeof a;if(b&&"object"==e)for(c in a)try{d.push(k(a[c],b-1))}catch(f){}return d.length?d:"string"==e?a:a+"\0"}function l(a,b){for(var c,d=a+"",e=0;e<d.length;)b[s&e]=s&(c^=19*b[s&e])+d.charCodeAt(e++);return n(b)}function m(c){try{return o?n(o.randomBytes(d)):(a.crypto.getRandomValues(c=new Uint8Array(d)),n(c))}catch(e){return[+new Date,a,(c=a.navigator)&&c.plugins,a.screen,n(b)]}}function n(a){return String.fromCharCode.apply(0,a)}var o,p=c.pow(d,e),q=c.pow(2,f),r=2*q,s=d-1,t=c["seed"+i]=function(a,f,g){var h=[];f=1==f?{entropy:!0}:f||{};var o=l(k(f.entropy?[a,n(b)]:null==a?m():a,3),h),s=new j(h);return l(n(s.S),b),(f.pass||g||function(a,b,d){return d?(c[i]=a,b):a})(function(){for(var a=s.g(e),b=p,c=0;q>a;)a=(a+c)*d,b*=d,c=s.g(1);for(;a>=r;)a/=2,b/=2,c>>>=1;return(a+c)/b},o,"global"in f?};if(l(c[i](),b),g&&g.exports){g.exports=t;try{o=require("crypto")}catch(u){}}else h&&h.amd&&h(function(){return t})}(this,[],Math,256,6,52,"object"==typeof module&&module,"function"==typeof define&&define,"random");
// calculate the week number of the year, multiply by the current year, and use as seed for the random function.
function getSeed() {
var d = new Date();
d = new Date(Date.UTC(d.getFullYear(), d.getMonth(), d.getDate()));
d.setUTCDate(d.getUTCDate() + 4 - (d.getUTCDay()||7));
return d.getFullYear() * Math.ceil(( ( (d - new Date(Date.UTC(d.getUTCFullYear(),0,1))) / 86400000) + 1)/7);
// all participants in an array, with a function to splice one random element out of the array and return it
function grabNext(){
var r = Math.floor( Math.random()*ppl.length );
return ppl.splice(r,1)[0];
var ppl = [
"Adam Adamsson",
"Anne Anderson",
"Cecil Cecilsson",
"Christof Christofson",
"Dana Dansson",
"Denise Dennisson",
"Erica Eriksson",
"Fred Fredson",
"Fran Fransson",
"Helen Henricsson",
"Henriette Hansson",
"John Johnsson",
"Johanna Johansson",
"Magnus Magnusson",
"Martina Martinsson",
"My Matsson",
"Nathalie Nilsson",
"Peter Peterson",
"Petter Pettersson",
"Sandra Samsson",
"Tommy Tomsson",
"Toby Tobiasson",
"Tor Thorsson"
var maxGroupSize = 4;
var groupCount = Math.ceil(ppl.length / maxGroupSize);
var g=0;
var groups = [];
// keep taking random names from the ppl array, and add them one after another into the different groups.
while( ppl.length > 0 ) {
if( groups[ g%groupCount ] === undefined ){
groups[ g%groupCount ] = [];
groups[ g%groupCount ].push( grabNext() );
// write the result to the #group div
var groupNames = ["I","II","III","IV","V","VI","VII","VIII","IX","X","XI","XII"];
var str = "";
for( var group in groups ) {
str += `<div class="col-md-6"><h2>Grupp ${groupNames[group]}</h2><ul class="list-group">`;
for( var p of groups[group] ){
str += `<li class="list-group-item">${p}</li>`;
str += "</ul></div>\n";
document.getElementById("groups").innerHTML += str;
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